DSB Heresy

[ldrhawke]

I am posting this in several forums of RC and it follows discussions in other threads.

This is different filtration approach that is sure to cause controversy and sound like heresy to the DSB believers.

What my approach is not: It is Not Jauberet Plenum System and it is Not a conventional DSB. Although it uses somewhat similar process components, it is not the mentioned systems because , for better words, they are stagnant systems. They are dependent upon some sort of natural flux to move waste through there process. It doesn't work.

For now, let us just call my approach, CPW (Controlled Plenum Wasting).

I know the DSB followers will say come back in 5 years when you have proven it works. My response is it does not take years to prove positive results and the system can at any time be made into a Jauberet of DSB by simply not using it, so there is no risk in using it. I also believe for newly established systems, that are set up with CPW, reef keepers will have a much greater chance of long term success.

CPW is based on and assumes the DSB and the Jauberet systems do not work well as biological filters. That is not to say oxic and anoxic biological filtration is not taking place in them, but that it is just terribly inefficient and uncontrolled biological filtration. It assumes at best you can walk a tight rope using them, and make them appear to be functioning, only to have a disaster a few months or years into their operation. If these systems are kept biologically very lightly loaded they may appear to be functioning, when they in fact may be doing more harm than good by slowly or abruptly allowing uncontrolled anoxic septic fluid to flow back into the system or deal with a potential death bomb if you stir up the bed.

If the above is true, why should I not simply use a BB (bare bottom)? The more biological useable and functioning biological surface area you have in a tank the better. It helps to keep the tank stable from the increased biological loading when sudden death or overfeeding occur. It is the same reason the use of live rock has been so successful in making reef tanks possible.

CPW (Controlled Plenum Wasting)

1. It assumes the fluids in the bottom of a DSB are anoxic and are not fully stabilized.

2. It assumes anoxic waste can buildup at a faster rate than the available bed active biological surface can fully stabilize it.

3. It is designed to remove unprocessed or reconstituted nitrates, nitrites, ammonia, phospahtes and other organic waste that accumulates in the bottom of the bed.

4.It assumes DSB and Jauberet designs are not 100% effective in biological stabilization, and infact do cause a major build up of anoxic Hydrogen Sulfide in the bed that does and can leak back into the tank.

5. It is simply a method to compensate for this inefficiency.

6. It improves the DSB biological efficiency by moving fresh food into the zones.

First I will address a major DSB and Jauberet process fallacy often stated.

1.) Anaerobic processing is completely stopped if anoxic fluid( partially oxygenated) moves into a DSB zone and it takes weeks to recover. All of the waste I remove does not show that to be factual.

You do not need or want large low or no flux dead zones in a DSB. You want a positive low transport rate of fresh septic material into and out of these zones. Depending completely on critters in a bed to do this is foolish. Most critters do not like to go into the large anoxic sulfide laden zones that quickly build up.

What is CPW (Controlled Plenum Wasting)? I will given a concise description of how I built my system and how it works. It is not very complex or should it be highly controversial, except for the fact that it may be viewed a heresy by advocates of DSB's. It is really based on common sense. It simply keeps a more positive flow into the bed and not back out into the tank water column.

In my system I have installed a plenum piping system, at the bottom of the bed, with relatively low very small number of orifices. I do use a coarse uniform agronite crushed coral as a DSB media (Carib Sea Special Grade Sand). This is all to assure of a more even flow distribution across the bed. A conventional commercial bottom filter, with is large open area, can and will rapidly short circuit the flow.

On a daily basis I drain the plenum of a couple of pints of anoxic waste that accumulated.

That is all there is to the system.........

I have the drain valve controlled with an X10 switch and my computer. It drains out a small amount every 8 hours.

Set up- Reef Tank: 45g half barrel, 30Hx15Dx30W, 5" DSB with a plenum bottom filter from which I drain 1 couple of pints of waste daily, Carib Sea Special Grade Sand 40 lb, 40Lbs Fuji branch LR, 15 G BB Fuge, Kalk Reactor, Skimmer, Ozone feed.

Why do I say this approach works better than other approaches that try to neutralize all the waste within the bed. It is based on very obvious measured results over two months.

1. What is drained out is always anoxic and has a rotten egg smell. Not something you want to remain in the tank. The fluid drained is anoxic, pH of the wasted fluid is always .5 lower than the water column, three to four times high ALK readings in the wasted fluid; all of which are an indication of continuous biological sulfide processing taking place deep in the bed.

2. When I have purposely allowed even a small amount to this anoxic sulfide laden fluid to re-enter the tank, the tank ORP read out drops like a rock and takes nearly a half day to recover. Even with the addition of ozone into the skimmer.

3. I have stopped making weekly 25% water changes.

4. My ORP readings have never been higher, they are approaching 400 mv. . Infact they remain above the ORP 350 mv set point for ozone feed and are continuing to increase. Little to no ozone is now even being added to the skimmer.

5. My water quality continues to improve, and all of the coral are responding positively to the water quality.

Is the above proof positive that this approach has merit? It does for me. Sure I will continue to monitor and tweek the wasting rate to see if I can improve upon the result. I am sure other will improve upon this approach and I will continue to monitor and post the good and bad.

I have experienced no negatives. My tank is very stabile with very low ORP swings and much more rapid recovery. I no longer do weekly water changes, which was a pain in the butt. The total amount of water removed is a small fraction of that need during normal water changes.

Some of the other potential but unproven positives. (see the attached independent list of negatives from anoxic sulfide processing going on in a DSB.) This RC thread is on going and worth reading. http://reefcentral.com/forums/showthread.php?s=&threadid=263482&perpage=25&pagenumber=1
________________________________________________

http://www.ozestuaries.org/indicato..._reduction.html

Organic matter decomposition can be a consequence of sulfate reduction in the sediments of coastal waterways (and other aquatic systems) [1]. The process is performed by anerobic sulfate-reducing bacteria. The bacteria require: metabolisable organic matter ; an anoxic environment (or microenvironment); and dissolved sulfate. Hydrogen sulfide gas (H 2S) and alkalinity are generated in the process (see simplified reaction 1).

Consequences of Sulfate Reduction

H2S smells like rotten eggs, and can detract from the aesthetic amenity of coastal waterways when it is released to the atmosphere [2,5].

H2S is toxic to a wide range of aquatic organisms [3];

H2S can inhibit nitrification [4]. When nitrification is inhibited, coupled
nitrification-denitrification is also inhibited.

Ammonium (NH 4+) is released from organic matter during degradation by
sulfate reduction (Equation 3) [6]. Ammonium is a bioavailable and is
readily taken up by plants.

(Eq. 3) 106(CH 2O)16(NH 3)(H 3PO 4) + 53SO 42- “106 CO 2+ 16 NH 3+ H 3PO 4+
106 H 2O + 53 S 2- Iron sulfides ( e.g . pyrite), formed during sulfate
reduction, are an active component of acid sulfate soils (***),
and problems with acid production and drainage can arise if the pyrite
is oxidised .

Iron sulfides cannot bind phosphate . Therefore, when iron oxyhydroxides are converted to iron sulfides during sulfate reduction, phosphate can be released to the water column [9].
______________________________________________________________

The above leaves little doubt in my mind as to why a conventional DSB is a crap shoot and a ticking bomb. I will continue to run my experiment with removing this sulfide rich waste soup to see if a DSB can be made to work. Without a method of removing all of this bad soup from the bottom of any DSB I don't believe they can* work. *(can is relative. I mean eventually fail)

I personally believe your odds at the crap table in Vegas are better than you odds of having a reef tank using a DSB more than a few years before it flips or leaks back into the tank killing everything. If you had a strictly SPS tank with few fish you may beable to stretch the tank life out a few more years.

Phosphate non-binding can be a problem with a DSB, but the biggest advantage of a BB, and only using live rock, is that you have very little sulfate reduction zone to cause an upset. The negative is you have greatly reduced biological processing surface.

With a BB don't have a big hot cauldron of anoxic sufide soup that a DSB can produce. It is loaded with ammonia, nitrates, is nitrification inhibiting , toxic H2S laden, and an oxygen depleting soup building up in a DSB waiting to boil over and snuff out life.

[MarkS]

So, the tank is drilled with the valve below the tank?

[ldrhawke]

MarkS
So, the tank is drilled with the valve below the tank?

NO....not holes in the bottom, see my gallery. The bottom plenum is piped to syphon over the top of the tank and down. I purge air out of it using a reverse flow to fill it first. Once it is filled everytime I open the valve under the tank it pulls a syphon and drains the bottom.

[MarkS]

Cool.

I like this. It makes perfect sense and addresses the problems with DSB's.

[Tat2dBrownDude]

makes sense to me

[MarkS]

Do you do this as part of a water change?

[ldrhawke]

It replaced my 25% weekly water changes. It is actually small daily water change. The advantage is it is removing th most concentrated waste at the same time.

I add a few spoons of salt everyday to the sump to make up for salt and trace elements lost and maintain my 1.026 sg.

At this point I no longer see a need for separate water changes. The water quality has never been higher and the tank more stabile.

The small daily change also avoids the possible rapid S.G. and Temperture swings that a 25% water change can causes if the mix is not perfect, even though the swing has a mostly affect. The rapid change that can occur isn't always positive.

[stevemc]

Sounds like the start of something new and wonderfull that works! I have tried deep sand beds and plenums and found they do as you said, work fine until one day you need to tear it down, because it contains bad stuff. I cant control my phosphates in my DSB tank, and am going to tear down. I didnt quite know what to do, except maybe just a thin layer of sand. I have read a few things here in the past, maybe it was your post, and it gave me an idea, like yours. I'm going to do the same. Thanks! Steve.

[MarkS]

I think I'm going to give this a try in my next tank. What material did you use for the plenum? I did not see it in your gallery. Awesone tank, BTW!!!

[Fredfish]

Sounds interesting. To be sure, there are some long term issues with sandbeds.

I am not sure I understand how this gets around long term nutrient loading in a sand bed.

I thought that the nutrient buildup in sandbeds was in the form of organic solids, not just nutrients in the water trapped in the bed. Draining off liquid wouldn't help with this.

Since the exchange of water between the sandbed and the tank is very slow, I also wonder what happens to the hydrogen sulfide?

My water quality continues to improve, and all of the coral are responding positively to the water quality

Can you quantify the continued water quality improvement? Is it just the orp or is there something else you are measuring?

Also, could you describe how your corals are responding?

THe reason I ask these questions is that I am curious to know what changes in your tank have given you to believe that there is an increase in the quality of the water. The longer I keep a reef tank, the less sure I am that I know which changes in my tank are positive and which are not.

For instance, most people take it as a good sign when their tank stops procuding algae, yet, in the wild, without a huge number of herbiverous fish and other creatures, reefs would produce huge amounts of algae. We generally don't stock the same evel of herbivours in out tanks, so we get excess algae. Algae growth is a sign that we do not have enough herbivours in our tanks, not necessarily a sign of poor water quality.

I have been contemplating a similar change/addition to my sandbed only I wanted to continually drain some of the fluid from the bottom of the sandbed and reintroduce it to the system via the skimmer effectively turning the sandbed into a large denitrator. My logic is that this increases the efficeincy of nitrate reduction by pulling a larger volume of the tank water past the reducing bacteria, increasing the processing capacity. It still dosn't deal with the build up of organic detrirus in the bed though.

By the way, did you read the most recent Reef AquariumUSA? There is a really good picture of the "sand bed" located next to most of the barrier reef in Australia. If you look at the vast amount of sand compared to the reef, you begin to realize that we really do put a very heavy load on our sandbeds and it should not be surprising that there is nutrient build up.

Fred.

[ldrhawke]

http://reefcentral.com/gallery/showphoto.php?photo=16197&papass=&sort=1&thecat=500

I used 1/2" pvc pipe. About 30 (1/32") holes are drilled in it and it was covered with 2 layers of drainage cloth to keep the holes from plugging and to assure of a more even fluid flow across the DSB bottom. The coarse crushed coral covered it.

It is piped so that it can be run in reverse to unplug the holes. I have seen no reduction in flow so plugging is not a problem.

[ldrhawke]

I am not sure I understand how this gets around long term nutrient loading in a sand bed.

I thought that the nutrient buildup in sand beds was in the form of organic solids, not just nutrients in the water trapped in the bed. Draining off liquid wouldn't help with this.



The major premise of using any sand bed is to develop adequate bacteria within it to break down the detritus. Both the resultant finer detritus and bacteria become a food for other bacteria deeper in the bed as well as food for the coral. Draining off the bottom removes mainly unprocessed organic wastes that is now in solution or very fine particles.

Do to the lower pH present in areas of the bed, some people also believe that deposited phosphates may go back into or remain in solution deep in the anoxic bed zones. It is possible some phosphate may also be removed, but that is unproven and just theory.

I used to have a number small pockets of fine detritus that collected in still areas and pockets on the top of my bed. For what ever reason, after starting CPW (Controlled Plenum Wasting), I no longer have any pockets of waste on top of the bed. I am not claiming it is because of CPW. I am just stating an observation.

Also, remember I do not believe in using fine sugar sand. I believe it is far to dense and leaves little open area to allow adequate fluid flow. I use a very uniform coarse crushed coral that is designed for exactly what I want. Pore space for fluid movement to reach deep into the bed

Can you quantify the continued water quality improvement? Is it just the orp or is there something else you are measuring?

Also, could you describe how your corals are responding?

Your are right good water quality is a rather nebulous statement. I have reduced algae growth, because of low phosphate and nitrates is one of my criteria. I had a hair algae bloom just before I started CPW because my phosphate and nitrate readings were increasing. It is one of the reason I started looking for other solutions to maintaining lower phosphate and nitrate.

To be fair, I have also reduced my fish feedings and reduced lighting time, so again I am not claiming CPW stopped my algae growth. But, I believe it has helped.

What I have experienced is close to zero nitrate, nitrite, ammonia and phosphate readings in my water column. I believe the high ORP readings and rate of ORP recover response are significant. For the first time my ORP reading has moved above and stays above the 350mv set point for ozone feed. It used to stay right at 350mv and turn the ozone off and on continuously. As Chemical Randy has pointed out to me the meaning of a high ORP and what the readings indicate are very complex. It also will vary from tank to tank because it has so many variables that cause change.

I do think all agree a high ORP reading is better than a low ORP reading. I am getting my highest ORP readings I have had since setting up the system without the aid of ozone. Also I am getting very rapid ORP correction from its drop when I feed. I feel this is a positive sign, which I do feel CPW has contributed to happening.


I have been contemplating a similar change/addition to my sandbed only I wanted to continually drain some of the fluid from the bottom of the sandbed and reintroduce it to the system via the skimmer effectively turning the sandbed into a large denitrator. My logic is that this increases the efficeincy of nitrate reduction by pulling a larger volume of the tank water past the reducing bacteria, increasing the processing capacity. It still dosn't deal with the build up of organic detrirus in the bed though

Continuous low rate drain back into the tank has been tried before with little success. The conventional commercial bottom filter with a bubbler does that.

1. You do not want to put the waste liquor off the bottom back into the tank. I have found it highly polluted still and even small amounts will cause major negative swings in ORP that are slow to recover.

2. I also consider reprocessing or putting the waste liquor from CPW into further processing , like denitrification. After considering it , it just didn't make any sense, even if I could totally reduce all waste to zero. Why do it when you still should make partial water changes to replenish the strontium, molybdenum, etc that comes with a fresh mix and needed my the coral. I believe partial water changes are good and CPW does this automatically when I waste to the drain.

My sump has a float control for replacing the wasted water from CPW wasting with RO/DI carbon filtered water. Now all I do is add a few spoons of fresh salt mix daily to the sump to maintain the S.G. and replenish trace elements. It is a lot easier, cheaper, and more convenient that doing my weekly 25% water changes.

Keep in mind the whole concept of CPW is simple. Remove waste from where it concentrates.

All the measurements I make indicate I am doing that. There may be other long term benefits; i.e, improving the DSB performance as a bio filter, removing phosphate from the bed, etc. That has yet to be proven.

I do know my coral are all in full bloom and appear happier....if coral can be happy...:>)

I do know my ORP read outs are the highest they have ever been and very stable.

I do know that what I am wasting through CPW is not stuff I want to keep in the tank.

I do know that all I need to do is tell the computer to stop opening a valve every 8 hours for 15 seconds and the automatic drainage will stop. I will then be back to where I was before I started CPW.

What is the risk in using CPW? Zero! :rolleye1:

What is the potential upside.....
:eek1:

I like those type of odds....:smokin:

[Putawaywet]

Interesting concept and I'm certainly looking forward to more info on this as months go by.

But I'm curious about your autotmatic drain setup. Am I reading correctly that your computer removes the set amount of water from the plenum on a daily basis? If so, what happens if there is a mechanical failure during the actual drain process? Wouldn't a stuck valve in conjunction with the X10 module allow the tank to completly drain?

Other than that it sounds like you have a variable alternative to DSB's.

Me thinks this is going to make for some intersting and heated discussions with the mainstream folks ;)

Brett

[ldrhawke]

But I'm curious about your autotmatic drain setup. Am I reading correctly that your computer removes the set amount of water from the plenum on a daily basis? If so, what happens if there is a mechanical failure during the actual drain process? Wouldn't a stuck valve in conjunction with the X10 module allow the tank to completly drain?



Excellent point. There are several ways to address that issue.

The easiest being to use two spring loaded normally closed solenoid valves in series and install a small filter screen in front of both. If one of the solenoid valves should hang up with trash on the seat, the second will still close.

As example, an industrial solenoid valve like the ASCO Series 8260 with a plastic body are normally designed for million of cycles. The chance of both valves not functioning is at the same time is extremely low.

You can also design it so the waste discharge goes into a small stand pipe out side the tank that over flows just below the surface of the tank back down into the drain. That way with a valve stuck open, the most water that could be drained is the amount in the tank between the tank water surface and the top of the stand pipe. That could be kept to a couple of inches, so under failure the tank does not drain more than a few inches of water below the normal water height.

I presently use the first method. Although I could go directly to a drain, I presently go to a quart sample bottle so I can test the discharge wasted. My sample bottle sits in a small dish that drains back to the fuge, if for any reason I should forget to empty it.

[Putawaywet]

Ok, got you now. I'm just leary of a computer to an X10 to a mechanical valve. Somewhere, somehow Mr. Murphy will come a calling.

Well, if this is the beginning of a new trend you're going to have to make sure you get your name in there somewhere. What good is a lagacy if it ain't named after you :D

Best of luck to you.

Brett

[clsund]

Hawke, as others have said, very interesting and compelling thoughts. Do you have a drawing you could post so more of us could try it out?

[H20ENG]

ldrhawke,
This was done in about 97-98 or so by Tom (arrggh forgot his last name!). He used to write for Marine Fish Monthly.
He used drip tubing and fittings and would only drain a little bit once a month vs daily. He noted all the things wrong with DSBs and Plenums back then, and this was his fix for the plenum.
Not to rain on your parade. Please keep up the testing and improvements! I believe it can only help!
Chris

[ldrhawke]

He used drip tubing and fittings and would only drain a little bit once a month vs daily.

This is not even the same concept. Like most all of the past approaches I have read about, the idea was to remove fluid from the substrate at very low rates and very small quantities. The concept was to maintain zero oxygen and the anoxic condition in the bed and not stop denitrifcation.

I do not believe larged quantities of fluid wasting will stop the anoxic process. In fact it possible that stopping the sulfide reduction, will probably accelerate both nitrification and de-nitrification. Hydrogen sulfide stops both nitrification and de-nitirification.

My concept is to remove enough fluid to reduce or eliminate the anoxic sulfide reduction process as well as flush out unstabilized waste building up or remaining.

By reducing the amount of hydrogen sulfide or stopping the reaction, hydrogen sulphide and the other contaminants such as metals dissolved in the rotten egg soup, are less apt to bleed back up into the tank water column.

Also, many of past process that removed small amounts of waste from the substrate simply put the wasted fluid right back into the tank or attempt to reprocess it.

Dripping or removing a little waste once a month or even dripping daily will not have the same end result, not even close.

I love analogies...... the difference in removal quantity. I flush a pint out quickly. it would be like comparing the results when flushing a comode by using a squirt gun with quickly dumping couple of gallons in from the resevoir tank. It has a dramatic effect on the results.


Not to rain on your parade. Please keep up the testing and improvements! I believe it can only help!


Reefers are the most hard headed opinionated group on the WEB. :strooper: There has been a thunderstorm of reponse since I started discussion the issue:eek2: You've been nice.;)

Keeping you up to date. I am wasting nearly a quart a day. I have had a positive response the last few days.....The samples collected no longer have the rotten egg smell that they have had for weeks. This obviously leads me to believe sulfide reduction is slowing down. Hopefully nitrification and de-nitrification will now have more space and food available to increase.

althoght, the importance of efficient biological processing the bed is reduced when using CPW, because the waste is simply dumped in the drain, but a more efficient biological process in the bed wouldn't hurt anything. It would help assure if a rock is picked up or the sand stirred, a major upset is less apt to occur from the release of phosphate and nitrate back into the tank

Wasting a quart a day is only about 1:250 of my tank volume. I will continue to test to find the optimum quantity to flush.

I have stopped my 15% weekly water changes. This was 5 times the amount I am presently using to flush the plenum with.

[ldrhawke]

Hawke, as others have said, very interesting and compelling thoughts. Do you have a drawing you could post so more of us could try it out?

Thanks.....I will work on a drawing for the process component layout and post it in my Gallery and let you know.

[Putawaywet]

Chris,

You're not thinking of Thomas Frakes are you????

Brett

[Fredfish]

OK, so if I understand correctly, since you started this wasting, Your ORP has gone up, nitrates and phosphates have gone down, though this is also due to reduced feedings, algae growth has slowed/reduced.

Did you have any plans to increase your feeding back to previous levels to see what happens to your water parameters?

It is most interesting that the rotten egg smell is gone. I was wondering if you were draining enough liquid from the sand that it would have a permanent effect on the bacterial makup of the bed. It obviously does.

AK! Whenever I get involved with these discussions I end up with more questions than answers. Is there a relationship between nitrogen based reduction and sulfer based reduction? From my reading on coil denitrators, I got the impression there was; that sulfer based reduction started to happen once the nitrates had been completely reduced.

By the way, the link to the OZestuary site is broken. I couldn't find the page you were refering to. Interesting site though.

Continuous low rate drain back into the tank has been tried before with little success. The conventional commercial bottom filter with a bubbler does that.

True, but, in terms of nitrate reduction, the flow rate is critical. A conventional UGF probably has to high a flow rate to make the bed an effective de-nitrator. From what I understand, if the flow through the "denitrator" is to high, nitrogen reduction is incomplete, and you end up going backwards, converting nitrates back to nitrites.

The idea is to get the flow rate through the sandbed to the point where nitrates are completely reduced, but high enough that sulfer based reduction does not happen. That should mitigate ORP issues. It does not address nutrient export the way wasting does, but I plan to use an ATS style filter for nutrient exports.

I must say I find the idea of doing water changes using your system most compelling. Why not do water changes where they will do the most good?

It will be interesting to see how your system progresses over time.

Fred.

P.S. I am still interested in hearing what has changed withyour corals that leads you to conclude that they are more healthy.

[H20ENG]

Brett,
I dont think it was Tom Frakes, not 100% though. I need to dig out those articles.
ldrhawke,
I am curious that now you are not getting any H2S smell, that you may be overoxygenating the bed, thus turning it into a very slow UGF. Obviously you are testing the "liquor" (Oh yeah, I remember my wastewater days:) ), but how about DO levels?
Just thinking there may be too much of a good thing. At worst, it'll diminish the denitrators in the bed.
Forgive me if you are already on it, just thinking aloud:)
Chris

[ldrhawke]

Just thinking there may be too much of a good thing. At worst, it'll diminish the denitrators in the bed.
Forgive me if you are already on it, just thinking aloud

Can't have too much of a good thing if I am using the DSB mainly as a sink, and secondarily as a biological filter. I really don't care if denitrators diminish. When people stop trying to figure out how CPW is interfering with possible biological processing in the bed, they will have a better idea of what it is doing.

The concept of CPW is to maintain the aerobic processing in the upper area of the bed and also maintain a positive flow into the bed. I have not been measuring DO. It would be interesting but not a driving number.

The idea is to remove nitrates, phosphates, hydrogen sulfide and other organic waster that collects in the bed and also keep it from being released back into the tank. I am hoping it will improve the nitrification process by feeding it better and give it back the space that sulfate reduction is using up.

Accepting the fact that waste does accumulate in a DSB, it is also important to have adequate flow to remove it and not let sulfate reduction become dominate, which will stop the nitrification and denitrification that may be present. CPW will also help to assure that if the bed is disturbed what is release doesn't reap havoc and sudden death.

The reduction in rotten egg smell from wasting a quart a day is indication to me I am heading in the right direction.

What a lot of people are missing is the important of the physical method to accomplish this. It makes all the difference in the world as to the CPW process working well or not working. If you do not harness the natural behavior of fluids to follow the path of least as they are removed from a DSB, the chances of CPW working are greatly reduce. This is a major key success. I am applying some of the same hydraulic principles I have patented in composting.

Obviously over time and with more people using the concept we can start to narrow the band on the volume of the wasting and frequency. I would not be suprised if the volume of CPW increases, simply to assure of adding back trace elements in fresh salt mix. CPW may not be controlled by the minimim volume required to make a DSB a positive element in a reef tank and not the negative one that many people view it as now because of it's acting as waste collection sink that eventually boils over.

[H20ENG]

What about nitrate accumulation then, if the lower bed begins to lose its reducers? I believe that the "good" denitrification takes place without going as far as producing H2S. I understand your theory, but it seems you can do both- drain off the accumulated waste and do it slowly enough that the DSB can still denitrify.

[Shoestring Reefer]

ldrhawke-
One reefer has been using a DSB with plenum for 9 or 10 years successfully. I believe he is "aged salt". I don't know if he has flow through his plenum or not, but he may be worth talking to.

Also, you state (simplified) that using the plenum/DSB system and removing water from the plenum will help prevent phosphate from being removed; the widely believed problem with DSBs is phosphate buildup, and I have heard little about problems with H2S buildup (not that it doesn't happen, H2S just may be the cause, and reefers care about the phosphate). That's an interesting relationship, it may explain things.

[ldrhawke]

The major problem with trying to make any DSB affective in de-nitrification is the lack of volume in even a 6' bed. If you reduce the rate of fluids down to the point that it efficiently de-nitrifies, then the fluid throughput does produce enough volumetric turn over of the tank to keep nitrates from building up in the system.

De-nitrification is many times slower than nitrification. Yes you could build a large de-nitrification chamber to to accept the fluid wasted from the plenum....but why?

You go to all the trouble to recycle the water in the tank and add all sorts of fancy expense equipment only to then turn around and make water changes that exceed the amount you are wasting by using CPW. I hope to be able to eventually tune the wasting volume so that it totally eliminate the need for any water changes, above what is accomplished through CPW. It doesn't make any sense to complicate a simple process .

I maintain one key principle when I do process design work ....KISS. It is always the key to long term success. It is easy to complicate and an art to simplify.

[Fredfish]

The major problem with trying to make any DSB affective in de-nitrification is the lack of volume in even a 6' bed

I am not sure I agree with that. A clownfish breeder here on RC (rsman) manages nitrates in his breeding setup with a series of coil denitrators. Now, a sand bed, particularly if it has fine sand, should have a much higher effective surface area than a coil denitrator and so, should be more effective.

The concern I would have with "tuning" denitrification in a sandbed would be with channeling of water through the sand. I know nothing of fluid dynamocs, so don't know how water would flow through a sandbed in low volumes.

I agree with KISS. There are a lot of different ways to acomplish denitrification and nutrient export. I happen to like deep sand beds because of the fauna they produce. I also like the idea of gaining greater "value" out of all that surface area by using it in ohter ways. Wasting would be one way. turning it into a more effective denitrator would be another. Either one can be very simple.

Fred.

[BORECKI]

Originally posted by ldrhawke
............. I would not be suprised if the volume of CPW increases, simply to assure of adding back trace elements in fresh salt mix. ........
Good thought!
One thing I'd like to add is this; You state that you remove a quart of water in about fifteen seconds every eight hours. In other words you "pulse" the DSB. Which is completly different from what others have tried in the past.
So far so good..
BUT
One quart of water divided by the floor area of your tank is probaly on the order of a few millimeter at most of water hieght. To have the water move through the sand such a small distance in fifteen seconds may not be enough to move solids through.
Another concern I have is with the filter cloth possably cloging with solids over time. Would you concider doing one three quart pulse in stead of three seperate quart pulses in the same time frame? And is it possable to speed up the water flow during the pulse to helpe dislodge some of the 'pasty' solids during the process?
Boris.

[ldrhawke]

I am not sure I agree with that. A clownfish breeder here on RC (rsman) manages nitrates in his breeding setup with a series of coil denitrators. Now, a sand bed, particularly if it has fine sand, should have a much higher effective surface area than a coil denitrator and so, should be more effective.

The concern I would have with "tuning" denitrification in a sandbed would be with channeling of water through the sand. I know nothing of fluid dynamocs, so don't know how water would flow through a sandbed in low volumes.



I am nit sure that I follow your or that you understand what I have said.

De-nitirifcation does and will take place in a CPW DSB. It is just not adequate to handle the load. You will still have nitrates in the wasted fluid. So what. They are dumped in the drain.

Yes, you can denitrify in a coil or fluidized bed. It would cost to build and operate either of the size required. Why would you build a denitrification if you did not need to? You do not have to with CPW.

The gallonage of a denitrification is very close to the gallonage of your tank. It also should be a batch system, two systems in parallel, to be affect. This is what is used in municipal and industrial WWTP's.

Also, picture the problem of continuely recycling denitrified water back into the tank from a denitrification system!

I'll ask you with an analogy.

If you added a red dye to the water in your reef tank. The red dye representing nitrates. Then you slowly fed into the tank a whole tank of clear pure water, allowing the excess to over flow, how many complete tank changes do you think it would take before you had no trace of pink in the water? Because you do not have a plug flow, but a complete mix exchange, I'd guess 50 to 100 tanks.

Now you know why is is simpler and more positive to dump the concentrated plenum waste to drain.

[ldrhawke]

I am not sure I agree with that. A clownfish breeder here on RC (rsman) manages nitrates in his breeding setup with a series of coil denitrators. Now, a sand bed, particularly if it has fine sand, should have a much higher effective surface area than a coil denitrator and so, should be more effective.

The concern I would have with "tuning" denitrification in a sandbed would be with channeling of water through the sand. I know nothing of fluid dynamocs, so don't know how water would flow through a sandbed in low volumes.



I am not sure that I follow your statements or that you understand what I have said.

De-nitirifcation does and will take place in a CPW DSB. It is just not adequate to handle the load. You will still have nitrates in the wasted fluid. So what. They are dumped in the drain.

Yes, you can denitrify in a coil or fluidized bed. It would cost to build and operate either of the size required. Why would you build a denitrification if you did not need to? You do not have to with CPW.

The gallonage of a denitrification is very close to the gallonage of your tank. It also should be a batch system, two systems in parallel, to be affect. This is what is used in municipal and industrial WWTP's.

Also, picture the problem of continuely recycling denitrified water back into the tank from a denitrification system!

I'll ask you with an analogy.

If you added a red dye to the water in your reef tank. The red dye representing nitrates. Then you slowly fed into the tank a whole tank of clear pure water, allowing the excess to over flow, how many complete tank changes do you think it would take before you had no trace of pink in the water? Because you do not have a plug flow, but a complete mix exchange, I'd guess 50 to 100 tanks.

Now you know why is is simpler and more positive to dump the concentrated plenum waste to drain.

[ldrhawke]

sorry for posting twice ...tried to correct for my dyslexia.

Let me also add. Also, if you try to recycle waste and use denitrification, it may remove nitrates but it does not address the phosphate and other types of waste you may be also recycling.

[ldrhawke]

BUT
One quart of water divided by the floor area of your tank is probably on the order of a few millimeter at most of water height. To have the water move through the sand such a small distance in fifteen seconds may not be enough to move solids through.
Another concern I have is with the filter cloth possibly clogging with solids over time. Would you consider doing one three quart pulse in stead of three separate quart pulses in the same time frame? And is it possible to speed up the water flow during the pulse to help dislodge some of the 'pasty' solids during the process?
Boris.

I will be the first to state, I don't know how much of a wasting is needed. I am sure that as reefers get aboard and start to use CPW, everyone will all have a slightly different approach.

The nice thing about the CPW, the way I have set it up, is everyone is free and able to tune it in to meet their own needs. No two tanks size or need is the same. Size, organic loading, etc, etc are all different.

If you follow my recommendations for constructing the plenum, clogging and blinding will not be a problem. You are only removing a small controlled quantity over a large surface area.

There are no solids removed, the bacteria has eaten or dissolved them by the time they reach the plenum. You are removing a solution.

I no longer have any sign of detritus on the bottom of my tank.

Keep in mind what we are going from to. A conventional DSB without CPW is a dead end garbage can. Even though many DSB system have gone belly up in a couple of years. Some of these system, if lightly loaded have lasted for years.

With CPW you now have a positive movment and transfer in your DSB. It isn't going to take much transfer to make a significant positive change to the DSB concept. In fact you may not want anything but a very low flow to make it maintain the highest oxic processing rates.

[Shoestring Reefer]

Originally posted by ldrhawke
The major problem with trying to make any DSB affective in de-nitrification is the lack of volume in even a 6' bed.

A significant number of hobbyists will testify that DSBs have reduced there nitrates to zero, even in 6" beds. DSBs are good denitrators. Their issue is longevity, not capacity to denitrate.

Originally posted by ldrhawke
The major problem with trying to make any DSB affective in de-nitrification is the lack of volume in even a 6' bed. If you reduce the rate of fluids down to the point that it efficiently de-nitrifies, then the fluid throughput does produce enough volumetric turn over of the tank to keep nitrates from building up in the system.

I think what you are saying is that by introducing flow through the bed, you compensate for the lack of volume. Correct me if this is an incorrect interpretation.

Originally posted by ldrhawke

De-nitrification is many times slower than nitrification. Yes you could build a large de-nitrification chamber to to accept the fluid wasted from the plenum....but why?

Because:
-It has been used successfully in at least one aquarium for about a decade
-It requires no moving parts
-Its abilities and limitations are well understood
-It has ben studied long-term

Originally posted by ldrhawke

You go to all the trouble to recycle the water in the tank and add all sorts of fancy expense equipment only to then turn around and make water changes that exceed the amount you are wasting by using CPW. I hope to be able to eventually tune the wasting volume so that it totally eliminate the need for any water changes, above what is accomplished through CPW. It doesn't make any sense to complicate a simple process.
Compared to the DSB with plenum, you have added significant complication.

Originally posted by ldrhawke

I maintain one key principle when I do process design work ....KISS. It is always the key to long term success. It is easy to complicate and an art to simplify.

You presented a non-traditional DSB method with short-term success and claim it has significant advantage over traditional DSBs. I suggested you speak with someone with long-term success with another non-traditional DSB. Your response to that was dismissive. Based on your posts here and otherwhere on this forum, I get the impression you are promoting an idea in order to get recognition, rather than helping discover the truth. It is discouraging to see someone focus so much time and energy trying to convince people of the long-term viability of something with only short term success. DSBs also have the same short-term success; your method does not seem to provide no additional benefits. At this point, you have presented no basis for the claims that it is better than a DSB. You have theories, but so do many other people.

Originally posted by ldrhawke

What is the risk in using CPW? Zero!

What is the potential upside.....

I like those type of odds....

I like the odds, where's the proof. I believe stating that your alternate DSB method has zero risk is not justified until there have been many hobbyists with many years of success.

[ldrhawke]

You presented a non-traditional DSB method with short-term success and claim it has significant advantage over traditional DSBs. I suggested you speak with someone with long-term success with another non-traditional DSB. Your response to that was dismissive. Based on your posts here and otherwhere on this forum, I get the impression you are promoting an idea in order to get recognition, rather than helping discover the truth. It is discouraging to see someone focus so much time and energy trying to convince people of the long-term viability of something with only short term success. DSBs also have the same short-term success; your method does not seem to provide no additional benefits. At this point, you have presented no basis for the claims that it is better than a DSB. You have theories, but so do many other people.


quote:
Originally posted by ldrhawke

What is the risk in using CPW? Zero!

What is the potential upside.....

I like those type of odds....


I like the odds, where's the proof. I believe stating that your alternate DSB method has zero risk is not justified until there have been many hobbyists with many years of success.

No problem.....I really haven't follwed any of the logic of your comments, other than some sort of animosity......in 15 years give it a try.... or not.

Happy New Year

[BORECKI]

For now I am intrigued with the concept and am willing to try it in a future tank.
Mind you I came from growing Koi for sale (doing 50% water changes / week) to my current DSB. I started reefing with a BB (berlin sistem)and doing 25% water changes, killing fish & corals in the process. And thinking something is wrong with the concept. Till I found out about DSB's.
My current incarnation is a 65 show tank with 4.5 square feet of floor/DSB @4inches coupled to a 33long refugium/DSB (12X13X48) with another 4 square feet of floor/DSB @ 6 inches with linier flow across the lenth of the refugium (coral rubble above the sand.
Total DSB of 8.5 square feet and NO water changes in three years! Another note; the first time I got corals to grow & reproduce instead of dieing was after I want DSB.
About a year ago my A. clarke maited pair got fiesty with my other fishes and I banished them to the refugium (along with their BTA host. Mind you the free water hight in this tank is only 6 inches. So the first thing they did was to make more room for themselves by diging into the DSB a crater and moving the excess sand down stream.
They disturbed a square foot of sand down to the bottom.
Nothing happned!
No roten egg smell, no die off, nothing.
Having said that; lets say I'm a fan of DSB's in tearms of ease of maintenence, lower water changes, stabilaty, etc.
But what's being put forth out here is a good idea and I really don't see how it can hurt to try.
Until further info comes out, one thing I WON'T do is go back to bare bottomed berlin sistems.

[ldrhawke]

Originally posted by BORECKI
For now I am intrigued with the concept and am willing to try it in a future tank.
.................They disturbed a square foot of sand down to the bottom.
Nothing happened!
No rotten egg smell, no die off, nothing.
Having said that; lets say I'm a fan of DSB's in tearms of ease of maintenence, lower water changes, stabilaty, etc.
But what's being put forth out here is a good idea and I really don't see how it can hurt to try.
Until further info comes out, one thing I WON'T do is go back to bare bottomed berlin sistems.

When you get around to setting it up drop me a note and I'll try to help. Designing the plenum piping to get a more uniform flow through the substrate is important.

I am not surprise that you didn't get a rotten egg smell as the fish dug down. If any hydrogen sulfide was present it was being released slowly.

The more I experiment with CPW,the more I am convinced that sulfide reduction plays a bigger role in tank biological unbalance and shock than a lot of people think. It is easy to have are relatively large dead zones in a convention DSB where sulfide reduction can take over. If sulfide reduction takes over in the DSB and it becomes dominant, like a lot of reefer describe when digging a few inches into a bed and find a large black or gray zone, the fluid in this zone will cause a tremendous shock to the life in the tank if released quickly.

Try this experiment to get a better understanding of why I believe this. If you have a few feet of syphon hose around, drain a little of your tank water off the bottom, to fill it. Cap off the hose and allow the water to sit for a week before draining it into a glass. Smell the water.

You are never going to stop sulfide reduction in a DSB. It will always have dead zones, But, by using the Controlled Plenum Wasting (CPW) built as I describe, you will significantly reduce the amount of sulfide reduction across the DSB.

I feel this will opens up these dead zones and may allow the DSB to become more productive in both oxic nitrification and anoxic dentrification, making for even more productive DSB processing by slowing down sulfide reduction and also feeding the bed with positive flow and new fluid from above.

What is the basis of this premise? Right now I have very little rotten egg odor from my plenum wasting fluid. When I started CPW the odor in the wasted fluid would knock your socks off.

The first concern many reefers have when I describe this is that it will stop denitrfication, because of some more oxic fluid will move into the anoxic zone. I don't believe this stops denitrification based on my long term commercial experience in a very similar set of conditions when processing organic waste.

A DSB is not uniform with oxic and anoxic bacteria sitting in nice uniform layers. It has many many non-uniform zones in a continuous state of flux, moving from an anoxic state to oxic state and reversing depending on available food and oxygen. It is not this nice uniform layer of oxic processing the first 2 inches down and then all anoxic to the bottom often described by reef experts.

This is why many reefers find black sulfide reduction substrate just below the surface. But his is a whole new topic.

[ldrhawke]

Based on your posts here and otherwhere on this forum, I get the impression you are promoting an idea in order to get recognition, rather than helping discover the truth. It is discouraging to see someone focus so much time and energy trying to convince people of the long-term viability of something with only short term success. DSBs also have the same short-term success; your method does not seem to provide no additional benefits. At this point, you have presented no basis for the claims that it is better than a DSB. You have theories, but so do many other people.

For those reefers who read my ideas about CPW and feel the way "Shoestring Reefer" does, I have no need to blow my own whistle. I am simply passing on a concept that I believe has merit and potential.

I am new in reef keeping, but not new to biologically stabilizing detritus. I have been designing and building commercial waste treatment facilities for over 30 years. A single one of my processing facilities biologically stabilizes more human and animal detritus in five minutes than all of the RC reefer keepers and their tanks could produce in a life time. The treatment demands and obstacles are very similar.

I have added my company Website to my profile. Hopefully it will dampen insults.

[Shoestring Reefer]

Originally posted by ldrhawke
I really haven't follwed any of the logic of your comments
Ok, I felt that each of my comments specifically addressed the quote it followed. If there is any specific comment or question you would like clarified, feel free to ask.

[Shoestring Reefer]

I will try bo be specific and clear with this post.
Originally posted by ldrhawke

(Eq. 3) 106(CH 2O)16(NH 3)(H 3PO 4) + 53SO 42- “106 CO 2+ 16 NH 3+ H 3PO 4+
106 H 2O + 53 S 2- Iron sulfides ( e.g . pyrite), formed during sulfate
reduction, are an active component of acid sulfate soils (***),
and problems with acid production and drainage can arise if the pyrite
is oxidised .

Iron sulfides cannot bind phosphate . Therefore, when iron oxyhydroxides are converted to iron sulfides during sulfate reduction, phosphate can be released to the water column [9].
______________________________________________________________

The above leaves little doubt in my mind as to why a conventional DSB is a crap shoot and a ticking bomb. I will continue to run my experiment with removing this sulfide rich waste soup to see if a DSB can be made to work. Without a method of removing all of this bad soup from the bottom of any DSB I don't believe they can* work. *(can is relative. I mean eventually fail)

The logic presented above seems to suggest that phosphate is released because "when iron oxyhydroxides are converted to iron sulfides during sulfate reduction, phosphate can be released to the water column". Do you beleave DSBs have enough iron for this to be significant.

Are you suggesting that there can be enough iron in the DSB to be significant in terms of phosphate retention and release, yet low enough to not kill every invertibrate in the tank?

To be clear, let me phrase it another way: how much IRON do you beleave is in people's DSB.

[ldrhawke]

My wife is NOT impressed with how much I spent on Fighting Conch

Shoe String,

If your think your wife was not impressed with your Fighting Conch, trust me....I am even less impressed with what you consider to be an apology.

You are on my IGNORE LIST. I do not want to spend the time and energy trying to convince you of anything.

[MarkS]

I personally like your idea and it has merit. However, I do tend to agree with Shoestring Reefer. It is too new of an idea to prove conclusively. It may very well work like you say it will in the long term, but you've only been doing this for a few months. I'd like to see the results after a year or two.

It would really be nice if the "experts" would get involved in this thread. This is a perfect discussion for Dr. Ron and Randy Holmes-Farley.

[ldrhawke]

Originally posted by MarkS
I personally like your idea and it has merit. However, I do tend to agree with Shoestring Reefer. It is too new of an idea to prove conclusively. It may very well work like you say it will in the long term, but you've only been doing this for a few months. I'd like to see the results after a year or two.

It would really be nice if the "experts" would get involved in this thread. This is a perfect discussion for Dr. Ron and Randy Holmes-Farley.

Thank your Mark,

But I don't believe it takes a year or two to prove if a process is working. Results can be measured and analysised. That is not to say the concept cannot be improved upon. The whole concept of waiting a year or two is based more on how long it took for a lot of DSB's to flip, than how long it takes to do reasonable analysis.

If I took a couple of years to apply every new and logical idea I have come up with I would not be in business. If the Wright Brothers did it we would all still be on the ground. :lol:
Sorry, I just do not understand the ultra conservative logic. Especially if you plan on installing a new DSB. You know a large percentage fail within two year and a significant number more within 5 years. Installing a plenum system as I describe, that can be disconnected at anytime, is no risk. Please explain what risk you perceive, that cannot be corrected.

First off...I am an expert in what I do. I respect and often use the expertise of men like Ron and Randy. I take the biological knowledge of men like Dr. Ron and the high degree of chemical expertise from a man like Randy and apply it to work in the real world. I hold numerous patents in doing this.

I don't think Dr. Ron and I would see eye to eye, but I could be wrong he appears to be wavering. He has demonstrated he has a lot of emotional baggage tied up in his DSB and critter concepts. I do not believe they can be long term successfully applied as he recommends.

Randy and I have had some discussions and we agree in a lot of areas. see below. You should read the whole thing so it is not taken out of context. http://reefcentral.com/forums/showthread.php?s=&threadid=282806

LDRHAwke statement: As usual you are absolutely right from the biochemical reaction side, but you are leaving out a major driving factor, the physical aspect.....fluid flow.

In any bed of porous semi-solid material it is difficult to obtain uniform flow. What will always happen is maldistribution of flow causing all the uniform processing and layer theories to fall apart as the flow short circuits and takes the easiest lowest pressure drop area to move through.


Randy's response: I agree that fluid flow is potentially important, and it is my theory that some folks may see better results with a plenum than a non-plenum sand bed because the plenum itself may encourage slight fluid flow in and out of the low oxygen regions.

That said, I think that fluid flow that is different in different spots mostly makes the "depth" at which certain transitions take place not be uniform. If there is a slight downward fluid flow, then the transition between O2 and NO3- based respiration moves deeper. Likewise, if there is a slight upward fluid flow, then the transition between O2 and NO3- based respiration moves upward.

Additionally, I agree that blocked regions will become anoxic regardless of depth, and so can pop up most anywhere if such blocking actually takes place.

[Aged Salt]

WOW! I was just given a heads-up about this thread:mixed: As many of the posters know[from other DSB threads] my p/dsb system is now 10yrs.+ & I have not had any HA in my system:) With diligent funnel-syphoning & stirring-up the dsb, I have been able to keep exportation of waste in check despite a heavy bioload in which I feed the reef fish 3X's/d & maintain over 50 SPS's. I have found that doing this once/wk is necessary for my bioload. I personally like the plenum for denitrification & an marker for determining the depth of my bed cleaning[I NEVER disturb the plenum]. Idrhawke's system should work & may end up taking less maintenance. It takes me about 45min/wk. to clean 1/3 of dsb--just to give you all an idea of how easy it is to care for a p/dsb:) Bob

[chriskirby101]

Didn't A Thiel suggest this years ago??

www.athiel.com

[ldrhawke]

Thanks Doc,

I knew someone had to be out there already moving in the direction of CPW. It is just the next logical step to what you have been doing for ten years. It also may free up 45 minutes a week for you.... :rollface:

[Aged Salt]

IdrHawke:lol: actually been doing the same funnel-syphoning as I did back in the 70's when we used UGF. As far as I know, Albert didn't start publishing until the mid-80's[no virtual knowledge exchange/computers then as we have now]. The p/dsb concept became well known in the early 90's by Jobert & Thiel's marine monthly began running articles about same shortly thereafter. Bob

[ldrhawke]

Didn't A Thiel suggest this years ago??



A lot of good information and it confirms the value in CPW.

Theil's testing and set up was significantly different.

1. It was dripping back into the tank a small amount from the plenum. I do not agree with or the need to put the resultant anoxic sulfide soup back into your tank. Just because it is being diluted does not mean it is not having a long term negative affect or that you are not putting everything but nitrates back into the tank. Phosphate is certainly being recycled.

2. A convention plenum as he describes will cause short circuiting. If you dye traced it your would see all waste being removed is coming from right around the spot where the plenum discharges through the substrate. Little or nothing is coming from a few inches away.

3.By dripping you do not get a flushing action that helps to assure you have a more even takedown through the substrate.

4. With a grating system he describes you cannot get a uniform removal through the substrate bed.

These are significant process differences.

[Aged Salt]

IdeHawke, I don't recall those procedures from his publication but later his online service [about 1995, didn't have a computer:( ] gave those suggestions? Bob

[ldrhawke]

Thanks for the reference to Theil's work.
I find the independent test data he has accumulated and recorder for what happens in a plenum EXCITING.

I know he viewed it as negative and his conclusion states so, but he looked at the plenum as a glass half empty and not half full. There is a bright side to his tests.

It is verification of what I am finding. It is also verification that phosphates do accumulate in the plenum. It means that the plenum is a sink and collects and concentrates products we do not want in our tanks.

It means by using Controlled Plenum Wasting (CPW) these products can be and are removed from the tank.

_____________________________________________

Theil Report http://www.athiel.com/lib2/noplenum.htm


I started measuring the parameters of the water in the plenum after the sand was in the aquarium for one month. I then took measurements once a month at 30 days interval. The table below shows the results at timeframe 60, 90, 120, 150 and 180 days. I then skipped a few months in the reporting below (although the actual testing was done) and give you the results for the last months of the testing.

The method used for this was to insert a real small pipette through the sand layer and screening to the bottom of the tank so its end was definitely in the water that constituted the plenum. The glass pipette was left in place so no "holes" would be made (interestingly enough, it did not take long for that pipette, placed in the left corner of the tank, to be totally covered with coralline algae).

Below are the results for NO3, PO4, SiO2, pH and and O2. I did not measure any other parameters.

"the data below is based on 30 day interval reading from the plenum"


NO3 PO4 SiO2 pH O2
11 0.7 0.2 7.9 5.4
34 1.8 0.9 7.2 4.9
71 4.1 3.7 6.4 4.2
117 8.1 5.4 6.0 3.9
243 14.7 7.1 5.4 3.7

skipped a few months
for reporting purposes
_
520 19.4 11.3 4.9 3.2
614 21.6 14.7 4.9 3.2
803 23.4 15.3 4.7 3.2

It would appear that the progression of nutrients is gradual and upwards and that oxygen falls and so does the pH.

When I measured the pH after 18 months of running the tank and before taking the plenum out (that was an exercise!) the pH was actually 3.9 and the oxygen level had fallen to below 3mg/l. At that time NO3 was close to 900 ppm.

Of course to take all these test I had to use dilutions in certain cases as none of the tests measured in such high ranges. I remultiplied my results by the dilution factors to arrive at the end results.

Based on this test and a test on one small tank, for a shorter period of time where I discerned the same trends, the conclusion to be drawn from this in my opinion, that plenums pose a potential problem for the hobbyist and the animals in the tank.

Indeed:
These nutrients can leach back into the aquarium by means of osmosis
Any break or rupture or shallow area of the layers could result in these nutrients seeping back through into the water

If this happens to a large extent, the tank is going to be in real bad shape as large amounts of all the nutrients will suddenly mix with the tank's water.

If a slow osmosis of nutrients takes place, the tank will go through unexplained problems and algae outbreasks that cannot really be accounted for. Alternatively or in addition nitrate, phosphate and silicate may show up in the tank that the hobbyist cannot explain in terms of origin. Of course no one would suspect that the build up actually comes from nutrients that leach back into the tank's water from the cesspool of nutrients that the plenum has become.

For this reason I no longer use Plenums in reef tanks and no longer recommend them.

[Aged Salt]

Good post,IdrHawke; I believe the reason for low or no phoshates in my plenum is weekly removal of same via dsb cleaning. Remember, the old saw on dsb's was NOT to syphon or stirr-up the bed.....basically let it perform magic:D Bob

[ldrhawke]

I think you are right Bob.

Stirring up the bed weekly allows what may be accumulating in the bed to dissipate before it gets too concentrated and can do a lot of damage. It is exactly why you have had 10 years of service from your DSB/P.

There is no reason to believe the same basic thing is not happening in a conventional DSB. There could be several explanations as to why it may not be leaching back into the water column as easily as it did in Theil's testing.

1. Theil used a very coarse substrate above the plenum system. It allows easier diffusion back to the surface.

2. Either temperature or salinity changes of in the water column could easily force what is in the plenum to the surface.

3. DSB that use sugar sand are much denser and less porous, they do not allow the same fluid transfer as easily.

It would have been interesting if he would have done the same sampling in his conventional DSB tanks. I would bet he would have found similar readings. The difference simply begin that it isn't as easily fluxed back to the surface.

If you review Theil's data, the waste continues to increase in concentration. It is maybe even accelerating in concentration.

If you follow the time frame of going on two years, that kind of soup in the bottom of either a conventional DSB or a Plenum DSB could cause havoc when released back into the tank.

I goes hand and hand with the rash of failures in DSBs around two years.

[Shoestring Reefer]

Originally posted by ldrhawke
Shoe String,

If your think your wife was not impressed with your Fighting Conch, trust me....I am even less impressed with what you consider to be an apology.

You are on my IGNORE LIST. I do not want to spend the time and energy trying to convince you of anything.
I did not consider anything I said an apology. You are NOT on my ignore list.

[Aged Salt]

IdrHawke, anyone who has kept a bb tank prior to keeping a dsb, noticed the detritus build-up right on the tank bottom[concencentrated No3- & Po4-]. Of course, the same thing occurs in a dsb system but it is not easily seen. Bacteria assimilate this into the bed. One MUST export this waste, as we used to do with the UGF........funnel-syphon & stir-up[or blast with a PH] & run a diatom filter or canister filter. Bob

[ldrhawke]

One MUST export this waste, as we used to do with the UGF........funnel-syphon & stir-up[or blast with a PH] & run a diatom filter or canister filter

Hopefully CPW can either eliminate or greatly reduce the above.

I have been able to maintain an ORP reading approaching 400mv by wasting a half quart a day.

My ORP has had a difficult time staying much over 360 mv for the last few days. It still is maintaining a fairy high ORP with out the aid of ozone.

I have doubled my rate of wasting to see if wasting can control it and bring it back up again. It may take a week before I see a positive response.

[Aged Salt]

Ahhh...... IdrHawke, be careful, more will be less----decrease the ORP. Plz. report your readings,Bob

[Turtlesteve]

Idrhawke,

I am intrigued with this idea and i think it has a lot of merit. Frankly i'd like to see for myself whether or not it works so I'm considering experimenting with it some, provided i can figure out how to automate the process (I'm in college and sometimes I only get to check the tank once a week or so). I think i can implement it fairly easily without detracting from the asthetics of the aquarium.

My idea is to carefully push short pieces of pre drilled PVC underneath the rock structure which could be assembled afterwards. This would be drained by a length of thin tubing which will pass between the double walled AGA overflow, down the tank drain and into a waste container. Because it would be run through the overflow it will be below water lever the whole way and starting a siphon should not be an issue. One way to automate the system would be to wire the flushing and replentishing into the auto topoff of the tank.

I have a couple of questions for you:

In your opinion, would a slow drip from the plenum be effective provided the water could be removed uniformly across the bottom of the sandbed? If not, do you believe smaller flushes of 1 pint or less every hour or two would be effective?

How would you suggest implementing such a system on a tank with an already established DSB?

later,
Steve

[nysbadmk8]

funny thing as im in the middle of the same concept and adapting it to my new 210g tank, but im not useing "automatic" methods of draining because i belive that leaves room for failure, so water removel will be done manually at the rate of 2 gallons a day.

[ldrhawke]

Ahhh...... IdrHawke, be careful, more will be less----decrease the ORP. Plz. report your readings,Bob

Ahhh....what?:confused: ;)

The ORP is the normal reading without the addition of anything. An ORP reading of 400mv is considered good by everything I have ever read. My coral sure seem to like it. They remain in full bloom. I have no way of dropping it other than contaminating the tank.

If I throw the hydrogen sulfide wasting from the CPW it will drop it like a rock.

Rather counter productive don't you think.:lol:

[ldrhawke]

Originally posted by Turtlesteve
Idrhawke,

I am intrigued with this idea and i think it has a lot of merit. Frankly i'd like to see for myself whether or not it works so I'm considering experimenting with it some, provided i can figure out how to automate the process (I'm in college and sometimes I only get to check the tank once a week or so). I think i can implement it fairly easily without detracting from the asthetics of the aquarium.

My idea is to carefully push short pieces of pre drilled PVC underneath the rock structure which could be assembled afterwards. This would be drained by a length of thin tubing which will pass between the double walled AGA overflow, down the tank drain and into a waste container. Because it would be run through the overflow it will be below water lever the whole way and starting a siphon should not be an issue. One way to automate the system would be to wire the flushing and replentishing into the auto topoff of the tank.

I have a couple of questions for you:

In your opinion, would a slow drip from the plenum be effective provided the water could be removed uniformly across the bottom of the sandbed? If not, do you believe smaller flushes of 1 pint or less every hour or two would be effective?

How would you suggest implementing such a system on a tank with an already established DSB?

later,
Steve

I would not retrofit a set up tank place. You're at risk of losing everything. Plus I cannot see how you can install a decent plenum system that way.

[Aged Salt]

IdrHawke, I read your post such that you were going to increase the draw from the plenum[waste water]. If you're meaning increasing your vol. of water changes, you MAY realize a increase in the ORP. Bob

[ldrhawke]

If you're meaning increasing your vol. of water changes, you MAY realize a increase in the ORP. Bob

That's the idea. I want my ORP to be close to 400 mv , without having to use ozone to do it.

[ldrhawke]

Originally posted by Turtlesteve
Idrhawke,

I have a couple of questions for you:

In your opinion, would a slow drip from the plenum be effective provided the water could be removed uniformly across the bottom of the sandbed? If not, do you believe smaller flushes of 1 pint or less every hour or two would be effective?

How would you suggest implementing such a system on a tank with an already established DSB?

later,
Steve

Steve,

Sorry I just noted I didn't answer your questions.

If you look at the Theil study and how the waste concentrates in the plenum over time, which I believe also happens in any DSB w/ or wo a plenum, any method that removes that contaminated fluid deep in the bed is better than none.

I do think for long term success it would be better to design a plenum system that worked effective in removing fluid more uniformly across the bed. This is best done by starting from scratch and rebuilding the tank substrate.

Dripping is not as effective as a periodic flush. The flush will better assure of a more uniform fluid differential pressure across the bed and a more even removal of what is building up in the bed.

[Shoestring Reefer]

If anyone hasn't checked out ldrhawke's web site (below his avatar) you should. Overall, one of the better sites I've seen.

I think his idea for tank filtration has merit; it is the logic behind it, and long-term stability, that I would like to see validated.

[Algae Blenny]

So this is sort-of a constant, small, stable water change and almost a Protein Skimmer for your sand-bed. I like this idea, and I believe it has no risk, I would have used it if I was starting my tank now.

[Adam]

ldrhawk,

I like the general idea, but your recently dropping ORP raises concerns.

It makes alot of sense that the ORP would initially rise by removing the lowest ORP material from the tank (and possible limiting sulfur reduction).

The recent fall in ORP suggests that some other change has occured in the way that things are being processed.

Any thoughts?

Adam

[Adam]

Hi all,

I put this in a seperate post since it has a totally different point.

There was some early discussion about redundant solenoid valves and mechanically compled overflow/standpipe systems to make this system "drain safe".

It would be quite a bit more simple and elegant to direct the waste into an appropriately sized (an ordinary 1 gal milk jug for example) container placed in the sump. Any amount in excess of 1 gallon would simply overflow into the sump.

I really think that this is the least of the issues related to this idea. I personally can't see why such a simple chore should be automated. I just posted this since the concept may have application elsewhere as well as here.

And Shoestring and ldrhawk.... I would prefer that you increase my notariety by referring to this design as "The Cesnales flood eliminator device" from now on :rolleyes:

Adam

[ldrhawke]

Originally posted by Adam
Hi all,


It would be quite a bit more simple and elegant to direct the waste into an appropriately sized (an ordinary 1 gal milk jug for example) container placed in the sump. Any amount in excess of 1 gallon would simply overflow into the sump.

... I would prefer that you increase my notariety by referring to this design as "The Cesnales flood eliminator device" from now on :rolleyes:

Adam

If you read some of my early posts that is exactly what I have been doing for months to collect samples. I have a gallon jug sitting in a plastic pan that over flows into the sump.

Sorry, day late and dollar short.... NO.."The Cesnales flood eliminator device" :lol:

[Shoestring Reefer]

Originally posted by Adam
The recent fall in ORP suggests that some other change has occured in the way that things are being processed.

Any thoughts?

Adam
My thoughts:
It may be a short-lived trend, and bounce back up; be fixed by adjusting flow (as he suggested may happen, I think), or be totally unrelated. If a few other tanks get set up like this, we can know better.

The worst thing that can happen for this (or any) idea is for the tank to go bad for some totally unrelated issue, and be discredited.

[ldrhawke]

Originally posted by Adam
ldrhawk,

I like the general idea, but your recently dropping ORP raises concerns.

It makes alot of sense that the ORP would initially rise by removing the lowest ORP material from the tank (and possible limiting sulfur reduction).

The recent fall in ORP suggests that some other change has occured in the way that things are being processed.

Any thoughts?

Adam

if you use an ORP meter you would know they continuously are changing. Feeding drops it 20 to 40 points. Add back a small amount of stagnant water back into the tank and it will drop 100 points.

If I stop CPW the ORP steadily declines. CPW has already increased it well above where it has ever been before.

All it is indicating to me is that the very small amount I have been removing, compared to my regular weekly 15% water changes, may need to be increased to have long term stability.

[H20ENG]

"It would be quite a bit more simple and elegant to direct the waste into an appropriately sized (an ordinary 1 gal milk jug for example) container placed in the sump. Any amount in excess of 1 gallon would simply overflow into the sump"
This is what I've always done with skimmate. I dont want a fluke skimmer burp to flood the house.
Sorry, though, not putting your name on it:D
Shoestring,
Props for staying with the topic after some of the previous statements. A gentleman.
I think this is going somewhere, but definitely needs further analysis, espescially on a per tank basis where feeding and stocking rates are much different.
Chris

[Shoestring Reefer]

H2OENG-
I'll make keeping at it a new year's resolution.

[darrellh]

ldrhawke,

I would like to volunteer to be a guinea pig for your CPW method. In the next month or so, I will be setting up a new 90 gal RR and transferring the livestock and LR from my current 75 gal tank. It has a 4" DSB with sugar sized aragonite. In general I'm happy with my DSB, and I don't think it has crashed yet (1.5 yrs old). My major gripes at this point are the on-going cost (it needs a detrivore recharge) and the fine sand that is constantly being dug up and blown about. Also I would like to keep some of the animals that are no-nos for DSBs (blennies, starfish, etc). One other thing that's probably a bigger issue than I think, I'm OK with the DSB's appearance on the sides, but my wife hates it.

Until I read this thread, I was planning on going with a 1-2" CaribSea Reef Sand (1.0-1.7mm) bed in the new tank with a mud-based refugium. I would be willing to forego the mud if you would rather see the results of CPW without combining it with other methods.

I have a few questions/ideas I would like to get your feedback on:

1. You mentioned earlier in the thread that you had more info on building the plenum PVC grid correctly. Can you provide the details? What material do you recommend for screening the holes?

2. What detrivores should I seed the new bed with? Any problem with using a small amount of fine sand from the old tank?

3. Instead of siphoning water from the plenum, I was thinking of using a small timer-controlled pump. Using a restrictor valve, it would be possible to set different surge strengths.

4. I was planning to use 3 or 4 power heads that would come on briefly at regular intervals to stir up detrius from the bed. What do you think about programming these to come on just before the waste surge to minimize the amount of detritus that would be sucked into the bed?

5. What parameters would you like to see measured in the water column and/or waste water?

6. Do you know of any fairly inexpensive timers that could be used in place of a PC? I think requiring a PC might be the biggest obstacle for widespread acceptance.

Thanks,
Darrell

[sambo]

Very interesting.......I've been reading all I can on filtration for the last two months and had decided to build a plenum/DSB system. The idea of draining small amounts of the plenum water appealed to me, even though I could find no real info/data on doing so. I thought maybe I was just "being the engineer!"

I will be setting up a 225 gal tank in the next few months, hopefully by summer. I did have a couple of questions for you, Idrhawke.....

How deep is your crushed coral, and is all your sand above this CaribeSea Special Grade Levlor, or whatever? I had though that I would build a 1-1/2" plenum topped with 2" of crushed coral (5mm +/-) and then 2 - 3" of CaribeSea sand (1-3 mm =/-). Is this similar to what you have setup? Do I even need the CC? Several articles I have read regarding plenums recommend just using the medium grade arogaonite sand for the entire 4 - 5 ".

Thanks for the info.

[Fredfish]

I love threads that make me go and read other stuff to figure out what makes sense.

I came across this (http://www.rsmas.miami.edu/info/press-releases/ancient-coral.html) link in another post that I think has relevance here.

Coupled with some comments about sandbeds by Eric Borneman in this (http://reefcentral.com/forums/showthread.php?s=&threadid=249112) thread (page 2), it supports the hypothesis being put forward in this thread.

Essentially the fine sand beds we set up act in a similar manner to seagrass beds with their biodiversity, food generation for reefs and nutrient processing. The first article suggests that without regular flushing, in this case in Florida bay, we get excess nutrients and a system crash.

Interstingly, Eric does not like the idea of keeping his "seagrass" area in the same tank as his reef and thinks there is a good reason why reefs are not co-located directly next to seagrass beds.

Fred.

[ldrhawke]

Originally posted by sambo
Very interesting.......I've been reading all I can on filtration for the last two months and had decided to build a plenum/DSB system. The idea of draining small amounts of the plenum water appealed to me, even though I could find no real info/data on doing so. I thought maybe I was just "being the engineer!"

I will be setting up a 225 gal tank in the next few months, hopefully by summer. I did have a couple of questions for you, Idrhawke.....

How deep is your crushed coral, and is all your sand above this CaribeSea Special Grade Levlor, or whatever? I had though that I would build a 1-1/2" plenum topped with 2" of crushed coral (5mm +/-) and then 2 - 3" of CaribeSea sand (1-3 mm =/-). Is this similar to what you have setup? Do I even need the CC? Several articles I have read regarding plenums recommend just using the medium grade arogaonite sand for the entire 4 - 5 ".

Thanks for the info.

It is all Carib Sea Special Grade Sand and about 3 to 4" deep. It is important to maintain pore space to allow flow. If it is too dense, like sugar sand, detritus will block and fill in the small pores very rapidly plugging up large areas and keep then totally anoxic and useless because little food will be moved through it to feed the bacteria. Sugar sand does have more surface area, as Dr. Ron states, but it does little good if the bacteria is starved.

[ldrhawke]

Originally posted by Fredfish
I love threads that make me go and read other stuff to figure out what makes sense.

I came across this (http://www.rsmas.miami.edu/info/press-releases/ancient-coral.html) link in another post that I think has relevance here.

Coupled with some comments about sandbeds by Eric Borneman in this (http://reefcentral.com/forums/showthread.php?s=&threadid=249112) thread (page 2), it supports the hypothesis being put forward in this thread.

Essentially the fine sand beds we set up act in a similar manner to seagrass beds with their biodiversity, food generation for reefs and nutrient processing. The first article suggests that without regular flushing, in this case in Florida bay, we get excess nutrients and a system crash.

Interstingly, Eric does not like the idea of keeping his "seagrass" area in the same tank as his reef and thinks there is a good reason why reefs are not co-located directly next to seagrass beds.

Fred.

This is exactly why Bomber and others have gone back to a BB tanks. I just feel that it may be possible to make DSB's work better by using CPW and maintain the positive aspects of what comes with more biological surface area, using the fact that they accumulate waste to our advantage.

Only time will tell if my CPW concept can do this. Right now I have no doubt that CPW will at least extend the life of DSBs, hopefully indefinitely.

[ldrhawke]

I am happy to report, that after less than 2 days of using an increased CPW wasting rate of a gallon per day, my ORP is again moving back toward the 400 mv goal without the aid of ozone.:rollface:

The positive water quality response is much quicker that I anticipated.

[ldrhawke]

I may have over complicated CPW (Controlled Plenum Wasting) for many reading my automated description. Let me try an make it very simple to understand and build.

Any one that reads the Theil report ( http://www.athiel.com/lib2/noplenum.htm) will agree waste concentrates in the plenum and builds up. There is no logical reason to believe the same thing is not happening in any DSB, with or without a plenum.

If after reading Theils report and his data you do not feel the waste that builds up in a tanks substrate is a very real problem......don't read any further.

The purpose of CPW can be explained with three statements.

1. Flush the bottom of your tank periodically to remove the waste that concentrates there.

2. Build a plenum drain system that does that effectively


Automating the process, making it more efficient, making it remove waste more uniformly, etc, etc is all secondary.

A CPW plenum system can be built out of 1/2 " pvc pipe from Home Depot or your local hardware store for less than $20.00*. You are just laying out a grid of pvc pipe using as much pipe as you can squeeze into the bottom. It is connected with elbows, caps, crosses, or Tees, and a few valves to isolate and shut it off, so you have a single outlet to drain the grid through.

It is important to minimize short circuiting. Keep the size of the drain holes small. Use a 1/32" drill bit and a drill a single hole in the pipe keeping them about 2 inches apart. Wrap the piping grid with drainage cloth (also available at Home Depot in the garden dept.), to keep substrate from blocking the holes.

Using two elbows and a few lengths of pipe you can run the discharge line up and over the top of your tank to make a siphon. Your do not even need to drill a whole in the bottom of the tank.

You will need to Tee it into your recirculation system to initially prime and flush the air out of the line so it will start the siphon.

Cover it with a coarse sunstrate to allow uniform flow though the bed.

Good luck.

NO..... I DON’T WORK FOR HOME DEPOT:lol:

[BORECKI]

idrhawke ;
I am thinking that there might be some benifit by laying eggcrate over the 1/2 inch pips and placing the fabric over the eggcrate. That would creat a true plenium over the entire bottom of the tank as opposed to making a complex grid of pipes individualy wraped in fabric.
One other concern I am thinking about is that the sand grains will shrink in size over time(just like in a standard DSB) and this will still need to be addressed.
Boris.

[Shoestring Reefer]

Originally posted by BORECKI
idrhawke ;
I am thinking that there might be some benifit by laying eggcrate over the 1/2 inch pips and placing the fabric over the eggcrate. That would creat a true plenium over the entire bottom of the tank as opposed to making a complex grid of pipes individualy wraped in fabric.
That sounds like it may be a little easier to set up. You wouldn't need as much pipe with as many holes, for example, because the water from the bed would be drawn into the plenum, instead of the pipe.

[sambo]

Thanks

[ldrhawke]

Originally posted by BORECKI
idrhawke ;
I am thinking that there might be some benifit by laying eggcrate over the 1/2 inch pips and placing the fabric over the eggcrate. That would creat a true plenium over the entire bottom of the tank as opposed to making a complex grid of pipes individualy wraped in fabric.
One other concern I am thinking about is that the sand grains will shrink in size over time(just like in a standard DSB) and this will still need to be addressed.
Boris.

Boris,

As ususal the knot head from Groton doesn't have the slightest idea of what he is talking about. If he's an engineer, he must drive a train. I wish he would butt out and stop giving people advice and acting like he designed the process and is now the expert. He doesn't even understand the process. 48 hours ago he was posting it won't work.

The last thing you want is an egg crate plemun, it will short circuit the flow and you will end up with large areas in the DSB unflushed. The plenum I described is purposely designed to cause a pressure drop so you get an even draw of fluid across the total bottom.

[darrellh]

ldrhawke,

I understand that you are more concerned with conveying the basic concept of CPW, but automating anything with my tank is a big selling point for me, especially if it's not very expensive. Minimizing manual maintenance is one of the keys that first drew me to DSBs (live and learn) and now CPW. In fact it's a 3-for-1 deal. I'll be exporting waste, making gradual water changes, and enhancing the performance of my DSB (hopefully indefinitely) with one automated process.

As far as automating CPW without a PC, I just noticed that Drs F&S is selling a new Grasslin digital AC timer for $22 that has 6 on/off settings per day and battery backup. The description didn't say, but I'm assuming it has at least a 1 min programming resolution instead of the 1/2 hour you get with the mechanical timers.

Do you think using a pump instead of a siphon for waste removal has any merit? Wouldn't more pressure differential make for more even flow distribution?

Thanks for sharing your ideas.

Darrell

[ldrhawke]

Originally posted by darrellh
ldrhawke,

I understand that you are more concerned with conveying the basic concept of CPW, but automating anything with my tank is a big selling point for me, especially if it's not very expensive. Minimizing manual maintenance is one of the keys that first drew me to DSBs (live and learn) and now CPW. In fact it's a 3-for-1 deal. I'll be exporting waste, making gradual water changes, and enhancing the performance of my DSB (hopefully indefinitely) with one automated process.

As far as automating CPW without a PC, I just noticed that Drs F&S is selling a new Grasslin digital AC timer for $22 that has 6 on/off settings per day and battery backup. The description didn't say, but I'm assuming it has at least a 1 min programming resolution instead of the 1/2 hour you get with the mechanical timers.

Do you think using a pump instead of a siphon for waste removal has any merit? Wouldn't more pressure differential make for more even flow distribution?

Thanks for sharing your ideas.

Darrell

I believe like you do... automate it. I just didn't want people scared off feeling it was complex and expensive.

A pump on the rise pipe would work great. Like...Maxijet 400 Powerhead. Then plumb its discharge to waste. That way you can pump it to a remote drain.

The timer idea is good, except the 1 minute is a pretty long time to discharge only a gallon and the flow rate would be very low. It would reduce the flushing action.

One way to get around it would be to discharge twice as much everyother day.

A lot of different ways to get nearly the same end result. Welcome to the CPW Society. :rollface:

[Shoestring Reefer]

Originally posted by ldrhawke
He doesn't even understand the process. 48 hours ago he was posting it won't work.

When did I post that it wouldn't work? Seriously, find one post that I made where I said it wouldn't work.

Originally posted by ldrhawke

The plenum I described is purposely designed to cause a pressure drop so you get an even draw of fluid across the total bottom.

I work as an engineer doing hydraulic analysis for power piping systems at a company that (among other things) developes thermo-hydraulic software for the numerical analysis of piping systems. Some of the software has nuclear pedegree, meaning it meets the requirements of 10 CFR 51.

Many of our clients are nuclear power plants. Analysis I have personally done includes prediction of plant performance under LOCA (Loss Of Cooling Accident) contitions, to determine if the plants aux feed systems can deliver the required flow under DBAs (Design Basis Accidents).

I have read Crane 410 from cover to cover; I am writing an internal document considering the Crane methodology of flow distribution in various "tee" configurations to Idelchick's (spelling) method, which is more tedious to do in longhand (luckily it's in the software) but more accurate.

I have helped develope software that does some of the things mentioned above, in addition to other areas of engineering.

Originally posted by ldrhawke

The plenum I described is purposely designed to cause a pressure drop so you get an even draw of fluid across the total bottom.
Assuming the bed has equal flow resistance at all locations (ie., the same substrait used throughout, even plugging by detritus if that occures, etc.), the best way to have even flow across the bed is to have an equal pressure differential across the bed at all locations. The pressure at the surface of a bed in an aquarium will be constant; therefore, the best way I can see to have a uniform pressure differential is to ensure a uniform pressure in the bottom region.

I am not aware of any method that completely eliminates all channeling.

I believe a plenum would best accomplish this, rather than buried piping, because the plenum would establish a uniform pressure at the bottom of the bed. The holes in the pipe would draw water from the plenum, not the bed itself.

Also, pressure in the pipes will vary from location to location; that is the nature of flow, and the reason flow exists in the first place. The pressure gradient across the surface of a plenum would be more uniform because of the lower velocity at any one given point, compared to the differential experienced along the length of the pipe.

I'll state what I just said differently, to aid some people in understanding:
I believe that drawing water into a plenum instead of directly from the bed i would reduce channeling because of the two resons listed below:
1) The destination for the water as it exits the bed would be a plane pressure boundry, rather than several points
2) The pressure gradient of the planar pressure boundary will be more uniform than that of several point boundaries, each with it's own pressure.

Suggested Plenum Design: Boreki Method
The Boreki Method is a union of the DSB with Plenum design used successfully for approximatey 10 years by Aged Salt (Based on Dr. Rons method, but with an independently-developed maintenance methodology), and the experimental method of Idrhawke. It consists of a relatively coarse (compared to traditional DSBs) bed over a plenum. The plenum is comprised of a water-filled void separated from the bed by, for example, egg crate supporting a layer of finer mesh, or UG Filter.

The Boreki plenum contains two or more 1/2" pvc pipes, which are drilled along their length to allow water to enter the pipes. One suggestion for hole size and spacing is made by Idrhawke at the beginning of this thread. I recommend holes be placed near the bottom of the pipes rather than the top to place the holes further from the bed, reducing the contribution of localised low-pressure areas on channeling.

The pipes run the length of the tank and are connected at one end of the tank to a common riser, which exits the tank to a manually- or automatically-controlled drain system.

The egg-crate may be supported soley by the piping, or by additional supports if neccessary. The in-plenum drain piping should be spaced evenly, with the space between the piping and tank sides equal to 1/2 the space between pipes. In other words, for two drain pipes, place each pipe 1/4 of the tank width in from the side.

Please note, if you have a standard-sized tank for which an under gravel filter plate is available, that can be used in place of the piping, egg crate, and screen. Simply use the riser connections to remove plenum water from the system, rather than connecting them to a powerhead (which was their original design).

[ldrhawke]

Originally posted by Shoestring Reefer
[B]When did I post that it wouldn't work? Seriously, find one post that I made where I said it wouldn't work.


by Shoestring .......
[QUOTE]DSBs also have the same short-term success; your method does not seem to provide no additional benefits. At this point, you have presented no basis for the claims that it is better than a DSB. You have theories, but so do many other people.


by Shoestring .......
I work as an engineer doing hydraulic analysis for power piping systems at a company that (among other things) developes thermo-hydraulic software for the numerical analysis of piping systems. Some of the software has nuclear pedegree, meaning it meets the requirements of 10 CFR 51.

Many of our clients are nuclear power plants. Analysis I have personally done includes prediction of plant performance under LOCA (Loss Of Cooling Accident) contitions, to determine if the plants aux feed systems can deliver the required flow under DBAs (Design Basis Accidents).

I have just lost all faith in the infallabilty of our nuclear industry and now have a real fear of potential nuclear meltdown.

by Shoestring ......
I believe a plenum would best accomplish this, rather than buried piping, because the plenum would establish a uniform pressure at the bottom of the bed. The holes in the pipe would draw water from the plenum, not the bed itself.

Also, pressure in the pipes will vary from location to location; that is the nature of flow, and the reason flow exists in the first place. The pressure gradient across the surface of a plenum would be more uniform because of the lower velocity at any one given point, compared to the differential experienced along the length of the pipe.


The above is the most brainless flawed false bunch of spurios gobble degook I have ever read. Are you writing your own laws of fluid dynamics now.

by Shoestring .....
Suggested Plenum Design: Boreki Method. The Boreki Method is a union of the DSB with Plenum design used successfully for approximatey 10 years by Aged Salt (Based on Dr. Rons method, but with an independently-developed maintenance methodology), and the experimental method of Idrhawke. It consists of a relatively coarse (compared to traditional DSBs) bed over a plenum. The plenum is comprised of a water-filled void separated from the bed by, for example, egg crate supporting a layer of finer mesh, or UG Filter.


The word that comes to mind is plagiarism.

Or better yet I'll quote a bombastic flake who needs to get a life.....he has been on the RC list less that 6 months and makes over 100 balderdash posts a month and his tank hasn't even cycled yet.


by Shoestring ........
I get the impression you are promoting an idea in order to get recognition, rather than helping discover the truth. It is discouraging to see someone focus so much time and energy trying to convince people .......

[MarkS]

Look man, I like your idea. I think it's great and has merit. However, your cocky, arrogent attitude is REALLY getting on my nerves. Take you fight with Shoestring to e-mail or private messages. He has yet to post anything even remotely looking like a flame towards you and has taken your attacks in stride. I can say, without a doubt, that he is the bigger man.

You don't like him and that's fine, but this thread is on the verge of being closed due to you and that really ticks me off!

[Algae Blenny]

MarkS is right. Shoestring Reefer has done nothing except be skeptical.

[MarkS]

I'm just posting from my past experiences posting ideas on these boards. I got constructive criticism on more than 90% of them and welcomed it. I really hate it when people post ideas or questions, but refuse to accept advice and/or answers that go against what they already have in mind. If you don't want to be criticized, then your wasting your time posting.

Not all criticism is bad. If you are too narrow minded to accept constructive criticism, then don't even waste my time posting.

[Scleractinian]

Originally posted by ldrhawke
Boris,

As ususal the knot head from Groton doesn't have the slightest idea of what he is talking about. If he's an engineer, he must drive a train. I wish he would butt out and stop giving people advice and acting like he designed the process and is now the expert. He doesn't even understand the process. 48 hours ago he was posting it won't work.

The last thing you want is an egg crate plemun, it will short circuit the flow and you will end up with large areas in the DSB unflushed. The plenum I described is purposely designed to cause a pressure drop so you get an even draw of fluid across the total bottom.

I'll try to avoid being added to the 'knot head' list... and I'd like to emphasize that I'm in no way questioning that your idea has validity (or that you have the right to name, trademark, or patent anything that you'd like)... Please TRY not to take an of the following as anything but an attempt on my part to ask for your thoughts or clarification... I'm a lowly public sector employee, and certainly not a CEO. ;) ( <-- denotes good-natured sarcasm)

Could you elaborate a bit on the hydraulic problems with using eggcrate over the grid, as suggested?

If you're trying to avoid short circuiting and channeling, it seems that drawing a small volume from a more discrete plenum space would actually help to accomplish this... What if you placed a sheet of acrylic, perf'd with uniformly distributed orifices and sealed to the tank sides, over the eggcrate...?

I deal with design challenges of maintaining uniform distribution in wastewater systems (various synthetic media and soils) under positive pressure at least daily... but keeping small orifices clear under negative pressure isn't something I've ever really thought about.

Might you also consider and comment on what may be the relationship of the function of your process to the mode of 'wasting'... What would you think of a continouos (non-pulsed, dropwise or via peristaltic pump) withdrawl of 'liquor' vs. your your present method? Are you hoping to move solids through the bed... at relatively very low velocities and only intermittently? Seems slower, uniform flows might make for best hydraulic uniformity, but would perhaps not be compatible w/ the chemistry desired...?

Also, have you considered testing your 'liquor' for PO4, Nx, etc? Might be interesting to relate what's coming out w/ your observed RedOx in another part of the system.

I just stumbled across this thread, and had been considering installing a small (2"x2") plenum connected to a 1/4" poly line to be sampled occasionally by withdrawl via a syringe (primarily 'cause I'm crazy and wanted to see what was going on in the sandbed) in a tank currently being assembled. I might just scale that plenum up a bit.

BTW, Though I've recently worked mostly with the other end of the system (the drinking water end), I'll have a chance to learn more next week about my first love: small scale sewage treatment ! (53rd Annual Michigan Onsite Wastewater Conference) I'd like to run some of the content of this thread by a few others who, like myself, and it appears, you, who are fascinated with what to do with lotsa poo... :)

[Fredfish]

Now we are getting down to the design nuts an bolts. I like that.

I will shortly be setting up a tank where stagnant areas in the sandbed will be a concern. I am planning a mangrove and seagrass tank and may have as much as 6" of sand to support the mangrove and the turtle grass (if this is the grass I use).

Further, I will need to intentionally put organics (in the form of soil) into the lower layers of the sand to provide the nutrients needed to support both the grass and the mangrove.

All this has me thingking that wasting might be a good idea for this tank.

Scleractinian
"Seems slower, uniform flows might make for best hydraulic uniformity"

This is what I would have thought, but I have no experience or training to back this up. Does grain size of the media effect how much it channels?

Is their any need to vary the hole size as you get further away from the drain in order to ensure more uniform draw across the entire plenum/bed. I would think that the preasure differntial would drop the further you got from the drain. Again, no training or experience to back that up, just too many brain cells with nothign better to do at 1:00am.

Fred.

[darrellh]

Scleractinian,

I agree with ldrhawke on not wanting to use eggcrate. With ldrhawke's method, all of the pressure drop caused by siphoning is evenly distributed across the 1/32" holes (provided there is enough gridding to avoid pressure drops in pvc sections that are far away from the siphon connection). The reason the pressure drop occurs at the holes is that the area of all of the holes combined is small compared to the effective cross-sectional area of the pvc grid, which is why ldrhawke recommended using as much gridding as possible. Since each hole is the same size, the flow near each of these holes will be evenly distributed.

If you now put an eggrate on top of the pvc grid, then you have just created a new large cross-sectional path between the pvc holes and the substrate that will allow the flow from the substrate to take the path of least resistance. At first the flow may be fairly even thru the substrate, but as some areas become more clogged than others, the flow rate thru these areas will decrease. Then it becomes a vicious cycle where the areas with low flow become even more clogged.


For MarkS and others, please cut ldrhawke some slack. Arrogant or not, his ideas may have a big upside for the rest of us. Besides it seems to me that Shoestring developed the attitude first. I just wish ldrhawke had kept him on his "ignore list" like he said he was.

Darrell

[keman]

I'm new here but I'd just like to pipe in (pun, hah!) with a comment on the grid vs. tube idea. I've been reading this thread with amazing concentration tonight.. lots of interesting ideas.

To me I see the reason why uniform flow would exist with tubes vs. the grid for the following reason:

The 1/32" holes all combined under tight granule sand will likely flow less than the uplift siphon draws. This is the pressure drop, and why a steady even draw would probably be made. For example, ever -try- siphoning a tank _empty_ that had sand in it? You can have a puddle of water and no water with sand separating it. It just doesn't flow through the sand easily. It resists flow.

A good analogy would be having one pipe near the uplift tube that has a theoretical 6" round hole drilled in it (I know, ridiculous but work with me here) with screen over it, and that's it. Draw water from it, and that's probably the only area through the sand water will pass. The grid has an area even bigger than 6".. but wherever the draw tube attaches to it, I doubt water will come from more than a 6" diameter area around it.

Some food for thought on all this though. I'm setting up a new 90 gal reef with 200# of Southdown right now on this very night (or now 2:28AM morning, argh time flys) ... 1 pint of water went a long way to saturating that much sand. I can't say it holds more than a couple of gallons before rising above the sand while filling. So if I were to siphon off a pint, it isn't 1:720 of the total water. It's more like 1/10th of the water saturating the sand. That could be a lot. As in, enough to largly impact the anarobic activity going on by drawing the oxic area down significantly.

ldrhawke, you noted a large decrease in the odor of the murk in short order after starting this... maybe things have become more aerobic. This isn't necessarily bad, but it might not be good either depending on what folks are relying on their DSB to do.

It's stuff like this that makes me want to see this used by different people for a couple of years and compare it to their own results without it before using it myself.

Now, don't get me wrong-- I'm burying 1/2" PVC tomorrow. :) ... it just may be a year or two before I turn that valve. Maybe I'll turn it when I start thinking my DSB needs a flush ... ;)

[darrellh]

keman,

Since your right in the middle of adding water to a new DSB, I just wanted to make sure that you were adding saltwater and not fresh. A while back, there was a Dr. Ron thread that said a freshwater saturated DSB could take weeks to equalize salinity throughout the DSB to the point where it could begin cycling.

Darrell

[keman]

Hmm... (bleary sleep depriven gaze)

Uh..

Yeah. Looks like I'll be stirring that sand up quite a bit tomorrow when I add that PVC... and salt. :P

Thanks for the reminder... yeah, salt was going to be added tomorrow. This tank hasn't held water since it was moved and I figured I'd reduce the damage potential by letting fresh water sit in it overnight. I didn't want to add the sand to the water and then deal with a thick layer of thin sediment settling on top.. but it looks like that'll be the case regardless.

I had a marine tank split open and dump 80 gallons of salt water onto the floor once. Bottom seam let go. 2nd floor. New tank, did it overnight. $8000 damage to the house. Saltwater ran down the furnace ducting and even ruined the furnace motor... :(

[H20ENG]

Thanks Mark S,
Well said, and my thoughts exactly! Ldrhawke is obviously very offended at the slight criticism and skepticism, and has resorted to flaming personal attacks.
Ldrhawke, I must say this attitude and lashing out seriously detracts from my interest in what could be a GREAT thread. Why not gracefully answer everyones questions and skepticism and leave out the flames.
This is what RC is about, sharing ideas and thoughts. Thank you for sharing your technique, but know that with this many people reading this forum there are bound to be a ton of questions and a healthy dose of skepticism in EVERYTHING from salinity levels to bubble size.
Onward!!
Chris

[Shoestring Reefer]

Originally posted by darrellh

If you now put an eggrate on top of the pvc grid, then you have just created a new large cross-sectional path between the pvc holes and the substrate that will allow the flow from the substrate to take the path of least resistance. At first the flow may be fairly even thru the substrate, but as some areas become more clogged than others, the flow rate thru these areas will decrease. Then it becomes a vicious cycle where the areas with low flow become even more clogged.

What you are saying makes sense untill you consider that, with the buried pipe idea, flow will not necessarily enter all holes equally, especially if the substrait gets clogged.

In other words, if the substrait gets clogged, I don't believe any method will provide uniform flow.

[MarkS]

Why not increase the diameter of the holes slightly as you get farther from the drain pipe?

[Shoestring Reefer]

Originally posted by Fredfish

Is their any need to vary the hole size as you get further away from the drain in order to ensure more uniform draw across the entire plenum/bed. I would think that the preasure differntial would drop the further you got from the drain.
Yes, with the pressure differential would drop as you get further from the drain-hense the plenum idea.

Bigger holes as you got further away would help; the problem is knowing how big to make the holes. The pressure differential will change as flow rate changes, so progressively larger holes best-suited for one flow rate (in terms of flow distribution) would not necessarily be best-suited for a higher or lower flow rate. I guess it would work if you vary the duration of draining, rather than flow rate.

If you decide to go that rout, pm me and I'll set you up with some formulas, if you're interested; ldrhawke may also be able to help, because that's sort of what his company does (but with air).

[Shoestring Reefer]

Originally posted by ldrhawke

I have just lost all faith in the infallabilty of our nuclear industry and now have a real fear of potential nuclear meltdown.

Um, "infallabilty"? Are you not aware that during the Three-Mile incident, PART OF THE CORE MELTED INSIDE THE CONTAINMENT VESSEL? Thats right, I've seen diagrams of where internals started, and where they ended up.

Seriously, it's nice to let yourself sleep at night, especially if you're downwind from a plant, but the system is NOT infallable.

Originally posted by ldrhawke

most brainless flawed false bunch of spurios gobble degook I have ever read. Are you writing your own laws of fluid dynamics now.

If you would like to discuss anything specific, let me know.

[BORECKI]

Originally posted by keman
..........Now, don't get me wrong-- I'm burying 1/2" PVC tomorrow. :) ... it just may be a year or two before I turn that valve. Maybe I'll turn it when I start thinking my DSB needs a flush ... ;)
Good thought on waiting for the sand bed to develop something before starting the flushing process.
Shoestring, and all others I'm no scientist, just a lowly driver with life expierence. My "gut" feeling still tells me that an eggcrate will work better in the long run without cloging.
From expierence; A while ago I had a 15 gallon DSB/refugium OVER a full size plenium (I could see into the plenium from the side){I have since swaped it out for a 33long, non-plenium DSB}. Over the two years that I operated this tank I noticed an acumulation of a very fine silt at the bottom glass. At the time I was using a UGplate as a seperator. At the time Jalbert mentioned an inch of free water as ideal so I added spacers to raise the plate. (hence the clear view under the plate) Over time I noticed silt droping down and the silt was distintly pilling up directly under the slits of the plate. If I remember correctly it was about an 1/16 of an inch of silt layer acumulated over two years.
WELL;I'm thinking that the volume of the plenium will give the DSB extra years of life before mecenical cloging of the pipes/holes simply by having a place for the mulm/silt to go to without blocking the 1/32 holes. Just have the holes placed on the side of the pipes and nether the top nor bottom so that they draw only water.
Another thing from expierence: I noticed that if I add more Ca (via KALK or calcium reactor) than my corals/halamidia/coroline algae use, the sand bed starts getting compacted regardless of how many worms are working the bed. And I have the full range of critters to work the bed. I have to go in and fork or finger the bed to fluff it up.
So in short, the Idea of CPW sounds realy good to me as a way of extending the life of a DSB and avoiding sulfide pockets. But I still feel that the sand will need replenishment and maintenence every now and then.
Another thought; For those of you that have or had UG plates. Dig them out of your attics and look at them. The slits are NOT uniform but vary in size as you go further from the riser tubes.
Addressing Keman's concern. Maybe a eggcrate is not the way to go but instead using the traditional UG plate. The variably sized holes might address the pressure diferential question.

Getting credit where credit is due;Shoestring My "method" is spelled, The Borecki method. :D
Boys; lets play nice!
Boris.

[Aged Salt]

IME with p/dsb, I've noticed thru the yrs. that from time to time the bed does develop areas of near-solid clumping, especially around the back areas that is difficult to funnel-syphon. I've had to use a ice pick at those times to return the "sand-rock" back to it's original consistency. This occurs from the varying levels of CA/buffer & KW drip & of course, would result in channeling. For CPW to function over time, this will need to be addressed with cleaning the bed periodically,Bob

[Aged Salt]

Boris, IMHP, I've always cleaned the bed wkly from the very beginning. I see no benefit in allowing nurient waste build up within the p/dsb & this allows uniformity in the system's parameters,Bob

[Scleractinian]

Originally posted by Scleractinian

What if you placed a sheet of acrylic, perf'd with uniformly distributed orifices and sealed to the tank sides w silicone, over the eggcrate, or just over a simplified PVC grid...?

AND

Might you also consider and comment on what may be the relationship of the function of your process to the mode of 'wasting'... What would you think of a continouos (non-pulsed, dropwise or via peristaltic pump) withdrawl of 'liquor' vs. your your present method? Are you hoping to move solids through the bed... at relatively very low velocities and only intermittently? Seems slower, uniform flows might make for best hydraulic uniformity, but would perhaps not be compatible w/ the chemistry desired...?

AS WELL AS

...have you considered testing your 'liquor' for PO4, Nx, etc? Might be interesting to relate what's coming out w/ your observed RedOx in another part of the system.



Just wanted to kinda bump a couple of parts of my previous post for all... Especially the sealed-drilled-uniformly-distributed-acrylic plenum (SDUDAP ;) ) idea.

And again... the sarcasm is friendly... I'm a Fluvial Geomorphologist/Ecologist mostly, not an engineer.

DarrelH and FredFish, I'm trying to avoid making up my own laws of fluid dynamics (another friendly ;) ), so I'd like to refresh my memory on the hydraulics of slow bed flows before I post anything that might cause people to lose confidence in either the safety of their drinking water or the function of their septic system... ;) (<---still meant in good humor)

[Aged Salt]

Scleractinian:crazy1: :lol2: Bob

[darrellh]

with the buried pipe idea, flow will not necessarily enter all holes equally, especially if the substrait gets clogged.

The area near each hole will have a higher flow and will tend not to clog. I agree that some clogging may occur between the holes and in the higher levels of the substrate, but at least you have some drainage at discrete points throughout the bottom. With a planar pressure approach, some large areas may shutdown entirely without any drainage.

One other thing to remember is the sand that ldrhawke is recommending is about 10x as coarse (1 mm min) than what Dr. Ron suggests for his DSBs. The coarser sand will tend to clog less (and blow around less...YEAH :)).

Darrell

[Shoestring Reefer]

I really think any way people want to set up plumbing-plenum or buried pipe-will probably be OK. That will ultimately be a trial-and-error/learn from experience kind of thing, and I suspect that some people will get either method to work, and some people will have problems with each method.

Two things that I DO think should be explored, at least for my understanding:
1) Phosphate retention and release.
2) The presumed function of the system.

1) Phosphate retention and release:
I think this must be addressed more in-depth because it appears to be the single-largest problem with DSBs. The initial post indicates that by preventing a pH reduction in iron-rich substrait, the release of previously retained phosphate can be prevented.
I am not aware of iron content in DSBs that is significant enough to be part of the driving force in phosphate release. If it is, or if the release of phosphate from calcium-based substraits is triggered by a similar condition, the information would be appreciated. The prevention of phosphate release is required for long-term function of the system.

2) The presumed function of the system:
If water is removed from the bed on a daily basis, or even more often, the detritus and nutrients in the DSB will simply be removed from the tank. Their removal suggests that any biological activity to break them down is not required, with the exception of providing food for tank in habitants (something that is questioned in DSB tanks). Mechanical filtration, such as wet skimming, and turf scrubbing, can perform a similar function of waste removel while preserving tank space, reducing set-up and maintenance complexity, and eliminating uncertainty. In addition, the coarse substrait means many botton sifters can not be kept, and the removal of flow from the bottom means burrowing animals can not be used. Edit<Basically, it sounds to me like a complicated system for mechanical removal and frequent water changes>
In other words, why not just run a wet skimmer and throw some macro algae in the sump? Edit<This system> may be "better than DSBs", but just because a bi-plane is faster and carries more payload than a write flyer doesn't mean we're using bi-planes for fighter jets.

Originally posted by BORECKI

Getting credit where credit is due;Shoestring My "method" is spelled, The Borecki method. :D
Boys; lets play nice!
Boris.
Oops, sorry. I kept spelling it Bohreki, as a matter of fact, and was pleased when I removed the "h".:p

[ldrhawke]

Questions by Scleractinian

I have no problem trying to answer your questions, as long as you are a "civil" engineer....a little humor back :strooper:

Could you elaborate a bit on the hydraulic problems with using eggcrate over the grid, as suggested?

Keep one basic thing in mind, which I know you understand. Fluids always flow to the lowest pressure area. Or to put it another way, fluids will find the path of least resistance and easiest way out of or into a container. This basic law of Fluid Dynamics is being ignored in trying to justify and make an egg crate plenum work.

When a fluid transfer system is being designed for low flow rates and low pressure. It becomes very difficult to control where and how fluid moves. The slightest change in resistance to flow will cause major maldistribution.

You have several ways to over come this problem, one is to increase the flow rates and/or increase the back pressure to obtain even distribution.

A grate plenum system will develop very little back pressure, unless you have very high flow rates. We don't have this in CPW so I have designed it to work for reduced flow rates.

Tank substrate is never perfectly uniform, and even becomes less uniform as detritus starts to fill voids, currents move the bottom around, and it ages. With low flow rates and low pressure the slightest variation in the bed density or depth will cause the fluid flow to that area or the slightest increase in backpressure will divert the flow around the area. With low flow rate systems flow can virtually stop into areas of very small increases of resistance.

As an example: The substrate bed in a tank is never perfectly flat. Density or porosity is not perfectly uniform. Also many tanks are set up with the substrate lower in the front of the tank and get higher in the back. If you had and egg crate plenum on the bottom you with very low resistance to flow, and if you removed a gallon of fluid from the plenum, what area on the surface of the substrate do you think the plenum would be replenished from.

Obviously nearly all the fluid would be pulled into the plenum from the front that has the shallowest depth and the lowest pressure drop. Little or no flow would come from the back.

Also when you pull the fluid out of the plenum, the closest lowest pressure drop zone, to that point of discharge, will be the area the fluid is pulled from.

An example. Exaggerated for effect. If you had your egg crate plenum 30 feet long and you where removing fluid from one end. How much fluid to you think would move down into the plenum chamber from the far end of the tank...Zero or non-measureable to be more accurate.


If you're trying to avoid short circuiting and channeling, it seems that drawing a small volume from a more discrete plenum space would actually help to accomplish this...

Ido not I understand your question? But drawing a small volume assures of short circuiting. You are not trying to avoid short circuiting as much as you are control it. Short circuiting will always happen. You are just trying to make it happen more uniformly and over a larger area.

What is your meaning of discrete plenum space?

Visual Maldistribution a couple of Examples:

Picture a 20 foot long piece of 1" pipe, capped at one end and connect a water hosed to the other end. The same size 1" hole drilled every 6 inches. To make it easier to visualize flow is out not in. (Fluid flowing in or out not much difference in the principle I want to demonstrate. ) Open the valve wide open hold the pipe horizontal with the holes up,. What do you think you will see. Most of the water will come out of the holes closets to the hose with the end. Make the 1" hole 1/32".....because you have water pressure and are restricting the flow, the water will shoot up a stream close to the same height uniformly from each of the holes.

1. If the pipe is large enough in diameter so it had little pressure drop from friction, water would shoot out of the all holes, and all the streams would rise to about the same height.

2. If the pipe was a small diameter you may have water shooting out at decreasing height as you moved away from the hose end.

3. Now take and add a very short riser pipe, 1/4" in height, to some of the holes. With high flow rates, which causes a pressure drop across the holes, the water will still shoot out relatively the same height.

Now slowly close the water valve and reduce the flow. As you reduce the flow you will see As you reduce flow, the holes slight 1/4" risers, will stop flowing any water at all and all the water would come out of the holes without the riser. That is caused by only a 1/4" in water column back pressure.

What does this have to do with a plenum on the bottom of the tank.....everything. The only way you can equalize the flow into or out of the plenum is to either increase the flow rate or reduce the outlet area, both of which are causing an artificial pressure drop. What you are doing is causing a controlled short circuiting. The more small holes simply control where you want the short circuiting to happen.

If you now covered this plenum piping I describe, or used no piping, and had the flow into our out of the egg crate plenum, which had little or no pressure drop at low flow. You would have accomplished nothing. You would be right back to the original maldistribution of the 20' long pipe with 1/4" risers.


What if you placed a sheet of acrylic, perf'd with uniformly distributed orifices and sealed to the tank sides, over the eggcrate...? This is probably the next closest approach that could be made to work. A sheet with a lot of small holes. The problem would be plugging. So to try and avoid plugging you would cover the holes with filter material. If you used a thick spun filter material, similar to the Poly Filter a lot of us use to remove phosphates, it would actually add a plenum space above the holes. For the most you would now have nearly the same maldistribution conditions your went to all the trouble to get around with a plastic sheet drilled with holes.


What would you think of a continuous (non-pulsed, dropwise or via peristaltic pump) withdrawal of 'liquor' vs. your your present method
This is back to the low flow condition which will cause maldistribution.

Are you hoping to move solids through the bed... at relatively very low velocities and only intermittently? NO....the idea is to allow the bacteria in the bed to eat the solids and only see waste in solution.


Seems slower, uniform flows might make for best hydraulic uniformity, but would perhaps not be compatible w/ the chemistry desired...?

Back to the maldistribution problem. The chemistry aspect is a whole topic by itself. The best rate of removal of the concentrating waste on the bottom of the DSB using CPW has yet to be established. What I am doing removing a gallon a day in a 60 gallon system works. It is optimum, probably not.

Several things affect this. Everyone's tank size and bio loading is different. Also, there is a lot of analysis to do in the chemistry of what is happening at the bottom of a DSB. The Theil data indicates that the build up of nitrates and phosphates may be accelerating with time and concentration of the anoxic sulfite soup that is building up. It appears that phosphates may be going back into solution which may be because of the chemistry and pH reduction. If that is the case, this could possibly be used to our advantage and allow us to remove more phosphate build up then we would get without the drop in pH. But, it also appears the reverse is true with Nitrates. They are also increasing which may indicate the sulfide reduction is taking over the bed and slowing the nitrate cycle down. So we may want to waste more frequently to stop that. This is a topic I am discussing with Dr. Randy or chemist whizard.

On the other hand, we may find wasting more once a week is more beneficial that wasting smaller amounts daily. This will only be know with more time and more study. I don't believe anyone reviewing the CPW concept and Theil's data can scientifically or logically reach the conclusion that a DSB will work better without using it.

Also, have you considered testing your 'liquor' for PO4, Nx, etc? Might be interesting to relate what's coming out w/ your observed RedOx in another part of the system.

You have not read or looked at the referenced sites at the beginning of this thread. Theil did an excellent study and collected great data years ago, the impact and significance of of this data has been ignored. It was for a DSB with a plenum, but I contend you would see very similar data from a non-plenum DSB. There is no sound logic to believe otherwise. A lot of study of this has been and is being done. It is the basis of believing CPW will benefit our tanks and improve water quality.

I just stumbled across this thread, and had been considering installing a small (2"x2") plenum connected to a 1/4" poly line to be sampled occasionally by withdrawl via a syringe (primarily 'cause I'm crazy and wanted to see what was going on in the sandbed) in a tank currently being assembled. I might just scale that plenum up a bit.

I am not sure that only doing CPW in a small area of a tank will demonstrate or prove anything.

All of the fluid flow principles, I am trying to explain, I have been using for 20 years in processing waste. There is little to no difference in how they apply and how they benefit fluid flow equalization. The same physical and engineering principles apply at the bottom of a reef tank or maintaining an optimum growth environment for microbes in our patented organic waste treatment process.

Plugging......I have been using the CPW plenum system I describe for over 6 months in my tank. The velocities are low enough to avoid rapid plugging. The flow rate of my system has not changed all, which would the indication of partial plugging. IF.... plugging did start to occur, I would simply back flush and open up the holes. All I need to do is open and close a couple of valves for a minute to accomplish this the way my system is piped. Just like is done with all sand filters in water treatment plants.

I have no intention of getting into any more ****ing contest trying to convince anyone, that uses this forum only to get attention and be noticed, that believes that water flows up hill and uses babble to prove it. I will discuss any topic or gray area on CPW with a "civil" engineer, or non-insulting lay person.

Babbling insulting idiots will be ignored. :p I think if you review my past posts, you will see doing it with a sense of humor has always been my manner. :mixed: :p

[Scleractinian]

Quote w/ commentary and clarifications

SNIP


You have not read or looked at the referenced sites at the beginning of this thread. Theil did an excellent study and collected great data years ago, the impact and significance of of this data has been ignored. It was for a DSB with a plenum, but I contend you would see very similar data from a non-plenum DSB. There is no sound logic to believe otherwise. A lot of study of this has been and is being done. It is the basis of believing CPW will benefit our tanks and improve water quality.

I did read them, might have missed this somewhere, but was just wondering if you were actually monitoring nutrient export via your system... and wondering if you could eventually relate easily monitored water-column ORP to what you're exporting.

If so, w/ an AquaController, for example, you might be able to automatically vary wasting interval and dose (I guess waste in this case) to compensate for change in system nutrient balance (accidental heavy feeding, algal succession, etc.)...

By more 'discrete plenum space' I meant sealing the acrylic to the aquarium sides... would a larger number (say every 1/4", OC) of small perf's in such a plate help w/ distribution... still (unfortunately) unclear as to how this might promote channeling more than the buried pipes would... BUT, as I noted, I'm no engineer (civil or otherwise, though my business cards have occasionally referred to me as one... noone knows what an RS or REHS is... in my State I can only cert designs up to 3000GPD) :)

Also, my intention in installing the tiny plenum in my system was for purposes of monitoring rather than processing. Might be interesting to install on a few exisiting DSB's to see how variable the chemistry is among different systems, especially over time...

I have no intention of getting into any more ****ing contest trying to convince anyone, that uses this forum only to get attention and be noticed, that believes that water flows up hill and uses babble to prove it. I will discuss any topic or gray area on CPW with a "civil" engineer, or non-insulting lay person.

Babbling insulting idiots will be ignored. :p

I'm an idiot... but I don't think I was babbling... :)

I think if you review my past posts, you will see doing it with a sense of humor has always been my manner. :mixed: :p

Thanks for this last bit... Humor's hard to convey via text, and harder so in forums such as this one.

[6 Line]

I am somewhat intrigued by the conflicting views on this system.
I for one would be greatful for more informative guidance on how to set up this system for my own Reef Tank.
I would be greatful for all relevant info to allow me to go and instal it into my new 5 x 2 x 2 Reef Tank with sump etc. Would also like some info on what constitutes a good sump design, and some good explination on how to design it.

I have run Plennums in the past and had to remove it from my old reef tank due to concreation. One point that I think was missed is that concreation of the substrate can be caused by Alk / Ca imbalance, thus it is crucial to keep in control (I was unaware of this at first, thus the concreation of my Plennum.)
I would like to point out that my aquarium looked magnificent whilst running the Plennum, it was only my uncertanty that made me remove it. I never had any traces on Ammonia, Nitrite, Nitrate, Phosphate (controlled by Rowa Phos)

Any advice will be greatly appreciated for my new design. I am not one to critisize, only add different perspectives.

Regards and thanks
Jay.
United Kingdom

:)

[Turtlesteve]

ldrhawke,

I was thinking some about pulling water from all areas of the sandbed, and i came up with an idea that i think might allow equal flow from everywhere while avoiding the problem of clogging easily. My idea is to use a pvc grid, but start at the center of the tank and repeatedly tee it off in a symmetrical pattern, and then cover the ends with a fine screen material. The idea by using a symmetrical pattern is that all the water being pulled from the sandbed, no matter where it is coming from, has to travel through the same number of tees and the same lenght of piping. I think this piping pattern would work in a conventional plenum as well.

I have attached a drawing of my idea (red arrows indicate flow direction). What do you think?

later,
steve

[ldrhawke]

.I am somewhat intrigued by the conflicting views on this system.

The only conflicting views are from people that simply do not want to accept the data below and feel they have some way to improve upon what I have described it takes to build a CPW system to work effectively.


This is the Theil report again.....


Below are the results for NO3, PO4, SiO2, pH and and O2. I did not measure any other parameters.

"the data below is based on 30 day interval reading from the plenum"


NO3 PO4 SiO2 pH O2
11 0.7 0.2 7.9 5.4
34 1.8 0.9 7.2 4.9
71 4.1 3.7 6.4 4.2
117 8.1 5.4 6.0 3.9
243 14.7 7.1 5.4 3.7

skipped a few months
for reporting purposes
_
520 19.4 11.3 4.9 3.2
614 21.6 14.7 4.9 3.2
803 23.4 15.3 4.7 3.2


This independent data. Not mine, although I suspected this was happening. This should give anyone looking at the data concern as to what is transpiring in any DSB w/or wo a plenum.

When the pH dropped into the 6's it appears phosphate starts to go back into solution. The problem is to get to a pH of 6 you need a pretty polluted sulfide reduction soup building in the bed. It's release and leaching back into the tank even slowly has rapid negative affects. I have demonstrated this in my tank on numerous occasions. A half cup full of this sulfide soup will drop ORP 150 points in minutes.

Without using CPW, it should be obvious where this data is leading. You have a DSB that is simply a garbage can starting to over flow.

Careful husbandry, monthly stirring, reduced Bio loads, will all help to push back the inevitable. Unless you remove it, the waste building is slowly leaching back into the tank. It has nowhere else to go

concreation What is concreation....it sounds like a cross between the theory of evolution and portland cement;)

This is not a static plenum system, as you used before. It has no comparison. As the data above should make clear. It is designed to remove that waste you had building in your plenum.



Scleractinian
Quote w/ commentary and clarifications

I did read them, might have missed this somewhere, but was just wondering if you were actually monitoring nutrient export via your system... and wondering if you could eventually relate easily monitored water-column ORP to what you're exporting.

YES..again reference back to what I have stated and published. I have been able to increase my ORP above the set point of ozone feed, by simply increasing the wasting rate. Which was initially on a couple of pints a day

If so, w/ an AquaController, for example, you might be able to automatically vary wasting interval and dose (I guess waste in this case) to compensate for change in system nutrient balance (accidental heavy feeding, algal succession, etc.)...

[/QUOTE] All possible, but over complicating a simple process may cause more trouble than it is worth.

By more 'discrete plenum space' I meant sealing the acrylic to the aquarium sides... would a larger number (say every 1/4", OC) of small perf's in such a plate help w/ distribution... still (unfortunately) unclear as to how this might promote channeling more than the buried pipes would... BUT, as I noted, I'm no engineer (civil or otherwise, though my business cards have occasionally referred to me as one... noone knows what an RS or REHS is... in my State I can only cert designs up to 3000GPD)

[/QUOTE] [ On a large flat plated, you will need a filter material covering the holes to keep substrate from plugging. The substrate will lay right on top of it. When you use a filter material like a spun fiber, its passages will reconnect all the holes and it will again become one large plenum that will cause significant short circuiting. A piping system I describe will still have some short circuiting but with the multiple independent legs, it is less apt to reconnect itself and become one large plenum again. We are trying to control the degree of short circuiting that will always occur[/B]

'm an idiot... but I don't think I was babbling...

I'm not sure about either..... :p

[6 Line]

SORRY FOR ASKING THE QUESTION!!!!!

I was not after more of the aforementioned insulting remarks that you seem to be directing at others on this board.
You seem too preocupied with your own self indulgance to read thoroughly the wording of the posted replys, to even acknowledge the fact that some on here actually believe in your modified system.
I was interested for you to pass on the correct way of installing this into my own aquarium without trying to decifer all the previous posts, however you seem to indulge yourself in trying to belittle everyone who comments on this quite complicated area that it is pointless in me trying to get any further information out of this post!!!!!

Regards
Jay.

:mixed:

[ldrhawke]

On second thought, there may be a way of making a flat plate work

By more 'discrete plenum space' I meant sealing the acrylic to the aquarium sides... would a larger number (say every 1/4", OC) of small perf's in such a plate help w/ distribution... still (unfortunately) unclear as to how this might promote channeling more than the buried pipes would...

If you took and layered out a grid of boxes with a raised 1/2" ridge to make the grid, on top of the flat plate. You could inserted small pieces of filter material into each grid square to cover the holes. The raised ridges would break up the continuous passage made by a single sheet of filter media. A little more complex but with merit if the system was mass produced.

[ldrhawke]

Reefer


SORRY FOR ASKING THE QUESTION!!!!!

I was not after more of the aforementioned insulting remarks that you seem to be directing at others on this board.
You seem too preocupied with your own self indulgance to read thoroughly the wording of the posted replys, to even acknowledge the fact that some on here actually believe in your modified system.
I was interested for you to pass on the correct way of installing this into my own aquarium without trying to decifer all the previous posts, however you seem to indulge yourself in trying to belittle everyone who comments on this quite complicated area that it is pointless in me trying to get any further information out of this post!!!!!

Regards


I thought the English had a sense of humor....sorry about the answer to yourquestion

"What is concreation? ....it sounds like a cross between the theory of evolution and portland cement"

I still don't know what concreation is?

Some times you English don't always say what we hear across the pond.

I remember staying in London at Jerrime Fry's flat. The maid asked me as she was leaving, "what time do you want to get knocked up."

I thought it was a great idea, I told he about 11 pm, she didn't see the humor either... :rolleyes:

[Scleractinian]

Originally posted by ldrhawke
.

Scleractinian
Quote w/ commentary and clarifications

YES..again reference back to what I have stated and published. I have been able to increase my ORP above the set point of ozone feed, by simply increasing the wasting rate. Which was initially on a couple of pints a day




OK. Again, I'm an idiot (seriously :) ), and I have re-read the posts here, and had (and have re-) read the Thiel info. I fully understand that the plenum space accumulates nutrients. I may have missed theanswer to the questions posed below, but I don't think so... The question that I'm doing such a poor job in asking clearly is this:

With your tank (utilizing the 'CPW' process), are you presently monitoring nutrients in your 'waste'... Are you checking PO4, Nx, etc, and logging it over time, especially w/ relation to observed ORP in the upper water column? Not 'has anyone done this' (I read the Thiel essay, and I don't think that many will disagree w/ his data, even if they disagree w/ his conclusions), but are you currently doing this?

I did realize that you are monitoring ORP w/ an ozone controller (see I read it above!) and that your ORP has shown a relationship to volume and frequency of 'waste' (told ya I read above!), even independent of O3 application.

What might be interesting is that one might eventually be able automatically control wasting using water column ORP as a signal to what's accumulating in the plenum... as you are doing manually now.

SO... are YOU testing YOUR the effluent for nutrients? If so, do you notice any relationship between nutrient levels in the effluent and the temporally related ORP observations?

And also, again because I'm an idiot (really, and probably babbling too ;) ) do you think that we should care about what's actually going on chemically in the plenum, or simply watch tank ORP?

And, as always... :)

[ldrhawke]

I was thinking some about pulling water from all areas of the sandbed, and i came up with an idea that i think might allow equal flow from everywhere while avoiding the problem of clogging easily. My idea is to use a pvc grid, but start at the center of the tank and repeatedly tee it off in a symmetrical pattern, and then cover the ends with a fine screen material. The idea by using a symmetrical pattern is that all the water being pulled from the sandbed, no matter where it is coming from, has to travel through the same number of tees and the same lenght of piping. I think this piping pattern would work in a conventional plenum as well.

I have attached a drawing of my idea (red arrows indicate flow direction). What do you think?



That will work. You will still need to cap the pipe ends and drill small holes in the pipe to equalize the flow. With open ends most of the flow would come fron the pipe opening closest to your discharge out let pipe.

You may find with all the connections, you will become size limited very quickly and have trouble fitting it on the bottom.

A simplier approach maybe a few straight runs made up of crosses with legs running off in both directions. Or a straight run the length of the back of the tank made from t's with legs running to the front of the tank.

There is no right or wrong way. You just want to cover the bottom with as much connected piping as you can fit into the tank.

[Scleractinian]

Originally posted by ldrhawke
On second thought, there may be a way of making a flat plate work

If you took and layered out a grid of boxes with a raised 1/2" ridge to make the grid, on top of the flat plate. You could inserted small pieces of filter material into each grid square to cover the holes. The raised ridges would break up the continuous passage made by a single sheet of filter media. A little more complex but with merit if the system was mass produced.

Since we could backwash, why worry about the filter media? What about filling the grid cells w/ a coarser, more spherical media (CC or granular dolomite maybe) before applying the SeaFlor Special Grade? Many columnar rapid sand filters use exactly this approach.

...or would backwashing aggressively enough to clear the orifices disrupt the substrate enough to make the microbes unhappy......

All... keep in mind... I'm an idiot (seriously) :wildone: .

[ldrhawke]

OK. Again....

With your tank (utilizing the 'CPW' process), are you presently monitoring nutrients in your 'waste'... Are you checking PO4, Nx, etc, and logging it over time, especially w/ relation to observed ORP in the upper water column?

I have been monitoring. There are continuous low levels of phopshate, pH, and nitrates in the wasted fluid....I have not mesured for SiO2.

There is little or no measureable level in the water column above. The most obvious thisng is the rotten egg odor present for several weeks in the low level wasting fluid. After a several weeks of wasting the rotten egg smell in the wasted fluid went away. The low levels of nitrates and phosphates remained. pH is always about .4 to .5 lower in the wasted fluid.

After about a month into my testing the ORP meter was struggling to stay at the 350mv set point even with ozone being fed, which indicated to me my water quality was dropping. WHich meant I was still leaching somthing back into the tank from the DSB. The measurements in the water column and the wasted plenum liquid were not varying much.

I decided to increase the wasting rate to nearly a gallon a day from 2 pints a day. This was still far below my normal water change volume. During all this time I have stopped doing water changes.

I was pleased to see the ORP start climbing, and move close to 400mv. All without changing the 350 mv set point for ozone feed. Presently it always remains above 350, unless I feed heavy, and then it dips for a few hours. The ORP readings have never been thsi high before.

Bottomline...CPW has eliminated my need to feed ozone to control ORP. The nitrate, pH, and phosphate readings in the wasted fluid remain very constant.


QUOTE]Not 'has anyone done this' (I read the Thiel essay, and I don't think that many will disagree w/ his data, even if they disagree w/ his conclusions), but are you currently doing this?[/QUOTE]

Yes..read above




What might be interesting is that one might eventually be able automatically control wasting using water column ORP as a signal to what's accumulating in the plenum... as you are doing manually now.

I have it on an automatic timer using an X10 controller and my computer. I know it can be hooked up to an even more automated system controlled maybe by ORP. I would not do this for two reasons.

Controlling wasting from an ORP meter would be a nightmare of over and undershooting. ORP response in the positive direction can take hours to work back to a high level. I am not sure you could control wasting from the readout without having a smart controller than learned.

SO... are YOU testing YOUR the effluent for nutrients? If so, do you notice any relationship between nutrient levels in the effluent and the temporally related ORP observations?

see above.

And also, again because I'm an idiot (really, and probably babbling too ) do you think that we shoud care about what's actually going on chemically in the plenum, or simply watch tank ORP?

Yes and No.....understanding what is happening more fully will probably help to learn more about wasting rate and frequency.

On the other hand, it appears so far that it is very easy to control water quality using CPW without knowing anything about the chemistry.

If you simply set up the system with an ORP meter and waste slightly more than is neccessary to keep it above 350, I don't think the most automated system or knowledge of the chemistry will neccesarily improve upon the end result. I could be wrong.

To put it another way...look at what most everone is doing right now in an effort to make DSB's amd BB's work. It is now almost accepted fact by most that DSB's will fail. The only question is when.

CPW is simplifying not complicating what exists.

This why I have trouble understanding all the debate. No one has been able to say to me look..."here is the potential damage and high risk you are causing my reef system by using CPW".

It's a no brainer to me. I wish someone could tell me what I am missing.

[Scleractinian]

Thanks for the response... and note that not everyone has questioned the premise of the process, and that at least a couple have primarily been trying to get enough info to implement it.

I'm still intrigued by the possibility of automating the release of effluent (hence my questions about monitoring the nutrient parameters of the effluent and about the dose/waste volume interval and periodicity)... I realize that the plenum ORP/tank ORP relationship wouldn't be quick or tight...

[ldrhawke]

I'm still intrigued by the possibility of automating the release of effluent (hence my questions about monitoring the nutrient parameters of the effluent and about the dose/waste volume interval and periodicity)... I realize that the plenum ORP/tank ORP relationship wouldn't be quick or tight...

One potential thing to monitor might be pH of the waste discharged. Keeping the waste in the DSB for more than 30 days appears to cause the pH to drop into the 4's.

If the pH is used as a control, as example, a controller could discharge at 4 and stop at 6. That may allow the DSB to drop low enough to allow phosphates and SI O2 to be removed. Just a thought. Needs a lot of testing to verify.

[keman]

Interesting question:

How much of a biohazard is the drained 'liquor' going to represent?

Should gloves be worn when handling the storage container for emptying, etc?

I grew up gravel vacuuming fish tanks, pulling dead fish out (worked at a LFS for many years) and eating food randomly always with bare hands. Never had any problems ... but.. this reminds me of a phrase I once heard:

"BMW Motorcycles never used to overheat.. until they started putting temp gauges on them."

[ldrhawke]

How much of a biohazard is the drained 'liquor' going to represent?

Should gloves be worn when handling the storage container for emptying, etc?



Easy with that biohazrd stuff.....we may have a greenie or an EPA advocate reading this stuff.

Next thing we know we will have to a a license to keep a reef tank and "big brother" will be monitoring our every move. We won't be able to empty any waste into the sink and we we all have to build a pretreatment plant or have a separate hazardous waste container at our drive way.. :bum:

[BORECKI]

irdhawke; perhaps a picture is worth a thousand words. Looking at your gallery, I did not see enough pictures of the actual under sand piping, nor how the holes are protected from cloging (the fabric). Could you be kind enough to make a mockup of a section of the pipe wraped with your fabric and post a few pictures?
Again; I don't think the concept of draining away the soup from the DSB is what's in question but rather the mechenics of the sistem.
turtlesteve; I think your idea of tuning the plumbing so that all the holes have an equalized distance/friction is a stroke of genius. (Just like tuned pipes of high perfomance cars & bikes)Taking that concept further, one can go a size smaller in plumbing (provided it's available at the local plumbing shop) and realy set up a very uniform grid on the bottom of the tank with LOTS of branches. One could even get out of the two dimentional drawing you did and go up with some of the cross pipes to crowd even more tubes under the sand. The end pipes would be at the bottom and the cross members one step above; the DSB will hide the whole thing anyway.

I only hope that raising questions is not a sign of being an idiot:mixed:
Boris.

[ldrhawke]

Originally posted by BORECKI
irdhawke; ... Could you be kind enough to make a mockup of a section of the pipe wraped with your fabric and post a few pictures?
Again; I don't think the concept of draining away the soup from the DSB is what's in question but rather the mechenics of the sistem.
turtlesteve; I think your idea of tuning the plumbing so that all the holes have an equalized distance/friction is a stroke of genius.

I only hope that raising questions is not a sign of being an idiot
Boris.


If I get some time, I'll try to mock up something so you can see a picture to explain the mechenics of the sistem. Right now I am not even sure if I will be in town next week.

There is no need to equalize the distance for the holes with 1/2" pipe only flowing a gallon a minute. There is no measurable friction loss in the piping to tune at this low flow a flow rate. It is only .04 ft of head loss per foot of pipe. Divide .04 by the number of total pipes, because the flow divided. You would have difficulty measuring any friction loss.

Questions are never a problem. It is arrogant condescending personal attacks that become a problem.

By the way didn't you run your plenum in reverse and clean the substrate regularly. I tried that for awhile but my water quality was a problem when I did it.

[Shoestring Reefer]

Originally posted by ldrhawke
I have been monitoring. There are continuous low levels of phopshate, pH, and nitrates in the wasted fluid....I have not mesured for SiO2.

There is little or no measureable level in the water column above. The most obvious thisng is the rotten egg odor present for several weeks in the low level wasting fluid. After a several weeks of wasting the rotten egg smell in the wasted fluid went away. The low levels of nitrates and phosphates remained. pH is always about .4 to .5 lower in the wasted fluid.
Ok, now maby we have a little data to work with, regarding long-term functionality. First, a some clarification:
Originally posted by ldrhawke
There are continuous low levels of phopshate, pH, and nitrates in the wasted fluid....I have not mesured for SiO2.
By low levels, do you mean that there are detectable levels, rather than undetectable levels?
Originally posted by ldrhawke
I have been monitoring. There are continuous low levels of phopshate, pH, and nitrates in the wasted fluid....I have not mesured for SiO2.

There is little or no measureable level in the water column above. The most obvious thisng is the rotten egg odor present for several weeks in the low level wasting fluid. After a several weeks of wasting the rotten egg smell in the wasted fluid went away. The low levels of nitrates and phosphates remained. pH is always about .4 to .5 lower in the wasted fluid.
In the first sentence of the second paragraph quited above, are you saying there are unmeserable levels of phosphate and nitrates in the water column, or just SiO2. I don't think ANY levels od SiO2 in the water column would make sense, but I want to make sure I understand what you are saying.

If there is undetectable levels of phosphate in the water column, yet you have detectable levels in the waste water, then the bed is already a phosphate source. The constant removal of waste from the bottom bed may help limit phosphate release into the water column, but what happens between the waste removal? Will phosphate retention and release continue to occure higher and higher in the bed, until it is close enough to the water column to affect water quality? Or, will increase waste removal eliminate phosphate in the waste water?

If, on the other hand, if phosphate levels are undetectable in the waste water and the water column (or can be made to be undetectable with increased waste removal), and can stay low long-term, then that would be a sign that phospate problems are a non-issue with this method.

[Shoestring Reefer]

Originally posted by ldrhawke

To put it another way...look at what most everone is doing right now in an effort to make DSB's amd BB's work.
What, exactly, are people doing to make BB's work that is not required with yuor method? From what I understand, the BB method requires skimming.

Originally posted by ldrhawke

To put it another way...look at what most everone is doing right now in an effort to make DSB's amd BB's work. It is now almost accepted fact by most that DSB's will fail.
Ok, so why not just go BB? What advantages does your idea have over BB? One original theory with DSB was that it would provide food for corals, and a breeding place for fauna like pods, etc, while providing biological filtration.

I have read numerous posts saying they believe the DSB contribute little to providing food for corals. I think your system would provide even less, considering the frequent waste water removal, which will just pull potential food away from the water column.

As far as a home for fauna, consider the recommendations for mandarines, which rely on pods for food. Recommendations are given for amounts of live rock and system maturity; substrait seems to be a minor consideration. Any fauna may end up too low in the bed to be of any benifit, anyway, because that's where the detritus will end up.

I think any biological filtration is irrelivent, becaust the water is just leaving the system, anyway. I'll let the town deal with handling my waste water.

[Shoestring Reefer]

Plugging of the holes is apotential problem; one recommendation for addressing that concern is to place "filter material" over the pipes (or plenum, if used) to prevent the plugging of holes.

The problem, as I see it, is that the filter material will still get plugged. That's why people using canister filters for circulation are recommended to remove the filter media.

A better solution may be to use larger diameter holes to allow detritus to pass through, eliminating the need for a filter material over the holes. The substrait used would be coarse enough to not blocg the tubes, and its coarseness will reduce substrait clogging, as well.

[BORECKI]

Originally posted by ldrhawke
..........By the way didn't you run your plenum in reverse and clean the substrate regularly. I tried that for awhile but my water quality was a problem when I did it.
No, when I was running a refugium/DSB over a plenium it was sealed as per Jalbert.
One thing I'd like to raise about the behavior of sand under water pressure; It will compact or turn into quicksand depending on the direction of the water flow. It should be quite interesting to see what happens to the sand with backflow pressure when one is uncloging any holes:D
Boris.

[ddoering]

Hi,

Interesting thread.

Isn't this basically an under gravel filter? You are proposing to use the sand bed for it's surface area, and instead of recycling the water passed through the gravel/sand, you are exporting it as waste.

Exporting concentrated waste is the most efficient I guess, like exporting macroalgae or using a skimmer to condense wastes into sludgey skimmate to remove from the tank.

Do you expect the bed depth to make much difference besides giving more area with deeper beds for more bacteria?

Are there some byproducts in the tank that won't be soluble and so will not be siphoned out over time? I thought that the problem with DSB over time was that they basically filled up and could no longer absorb more wastes. I thought this included solid wastes as well.

Would you expect problems with this using a shallower bed with finer sand (and smaller holes in the pvc?)

Do you have to worry about calcium carbonate buildup in the pipes which would require cleaning out the tubes? Having to try to tear apart a tank to get the pipes out to clean them would be like redoing a DSB tank in a few years to prevent old tank syndrome.

What is the real worry with DSB? Is it the accumulation of Hydrogen Sulfide? Or do people more have a problem with phosphate buildup and then algae nightmares?

The holes on the PVC, are you drilling them on the sides of the PVC, all around the PVC or what?

Thanks,
Doug

[keman]

Originally posted by ldrhawke
Easy with that biohazrd stuff.....we may have a greenie or an EPA advocate reading this stuff.

Next thing we know we will have to a a license to keep a reef tank and "big brother" will be monitoring our every move. We won't be able to empty any waste into the sink and we we all have to build a pretreatment plant or have a separate hazardous waste container at our drive way.. :bum:

Sorry, Biohazard was probably not quite the term I'm looking for. I doubt this stuff represents any hazard to the environment. Like any living environment though however, there will be some things that represent a hazard to us fleshy land dwellers. Someone brought up an interesting point on the topic of cutting live rock, for instance-- one I had not considered prior. Don't inhale the spray from a saw if you use one, as it can contain some very bad things.

What I'm interested in is how unhealthy this stuff would be to injest or otherwise come in contact with my skin?

Are we talking... rotting old hamburger unhealthy, or... ?

[ldrhawke]

Originally posted by ddoering
Hi,

Interesting thread.

Isn't this basically an under gravel filter? You are proposing to use the sand bed for it's surface area, and instead of recycling the water passed through the gravel/sand, you are exporting it as waste.

Exporting concentrated waste is the most efficient I guess, like exporting macroalgae or using a skimmer to condense wastes into sludgey skimmate to remove from the tank.

Do you expect the bed depth to make much difference besides giving more area with deeper beds for more bacteria?

Are there some byproducts in the tank that won't be soluble and so will not be siphoned out over time? I thought that the problem with DSB over time was that they basically filled up and could no longer absorb more wastes. I thought this included solid wastes as well.

Would you expect problems with this using a shallower bed with finer sand (and smaller holes in the pvc?)

Do you have to worry about calcium carbonate buildup in the pipes which would require cleaning out the tubes? Having to try to tear apart a tank to get the pipes out to clean them would be like redoing a DSB tank in a few years to prevent old tank syndrome.

What is the real worry with DSB? Is it the accumulation of Hydrogen Sulfide? Or do people more have a problem with phosphate buildup and then algae nightmares?

The holes on the PVC, are you drilling them on the sides of the PVC, all around the PVC or what?

Thanks,
Doug

Truely...not being a wise guy, but virtually everything you've asked has been answered if you start reading from page 1.

With regard to actual required service of A CPW system over time...only time will answer that. I'd just be guessing.

I don't believe calcium carbonate will build up in an area that tests show that pH's can drop well below 7.

[ldrhawke]

Originally posted by keman
Sorry, Biohazard was probably not quite the term I'm looking for. I doubt this stuff represents any hazard to the environment. Like any living environment though however, there will be some things that represent a hazard to us fleshy land dwellers. Someone brought up an interesting point on the topic of cutting live rock, for instance-- one I had not considered prior. Don't inhale the spray from a saw if you use one, as it can contain some very bad things.

What I'm interested in is how unhealthy this stuff would be to injest or otherwise come in contact with my skin?

Are we talking... rotting old hamburger unhealthy, or... ?

I wouldn't drink it :p


I'd be a lot more worried about the junk in my skimmer.....ikky, bad, no good, not nice:lol:

Just cleaned my skimmer out tonight:eek2:

[Shoestring Reefer]

Originally posted by ldrhawke

http://www.ozestuaries.org/indicato..._reduction.html

The above link is not working for me. I found the page here:
http://www.ozestuaries.org/indicators/Def_sulphate_reduction.html

[Randy Holmes-Farley]

The only conflicting views are from people that simply do not want to accept the data below and feel they have some way to improve upon what I have described it takes to build a CPW system to work effectively.

Just a comment here that we will probably address more in the chemistry forum. Note that some of these test kits involve redox chemistry. A little nitrite shows up as a lot of nitrate in some kits, for example. Since the plenum is a reducing situation where there may be redox species like nitrite and sulfite and other things, I tend to worry about the primary data that was generated by Thiel (not a chemist), and is being used to test these systems as well.

[ddoering]

Hello,

I did read through beginning at post one before posting my questions, and as I was unclear on things, I asked questions.

Simply referring me back to what I have already read does nothing to clear up any questions I have. If something was already stated, and somebody asks a question on it, try rewording your explanation, as this might clarify the issue.

Your first post states in the description of your tank you are using a 5 inch sandbed of coarser media than usually recommended for a DSB. Later you state it is between 3 and 4 inches.

You state you are using Carib Sea Special Grade Sand, which was later said to be approximately 1 mm (10x coarser than sugar sand).

"Also, remember I do not believe in using fine sugar sand. I believe it is far to dense and leaves little open area to allow adequate fluid flow. I use a very uniform coarse crushed coral that is designed for exactly what I want. Pore space for fluid movement to reach deep into the bed"


My question to this is what is the difference between using a coarser media 5 inches deep, or using a finer media that is perhaps 2 or 3 inches deep?

The smaller particles will provide much greater surface area for bacterial populations than the coarser media, so should improve the biological filtration.

You will not take up as much viewing area in your tank as a 5 or 6 inch bed if you could use a shallower bed with finer particles. You should still get the oxygen depleted areas without needing the same depth, but could prevent the completely oxygen devoid areas by reducing depth of finer grain substrate so it is not a DSB anymore.

Now I don't know about fluid flow, but wouldn't you be able to get adequate fluid flow through a shallower bed? Also, wouldn't a bed of finer particles help combat the channeling of fluid through an area of least resistance? I would think a coarser media would be more likely to channel, since the finer material would settle more and be moved around more by the water flow to fill in any channeling that occurs. You state that detritus will block pores in a finer substrate leading to dead zones. Wouldn't a finer substrate result in detritus being caught higher up in the sandbed in the oxic zone, where bacteria and microfauna can get at it? As opposed to it being sucked down so far into the coarser bed in an anoxic zone etc?

Using the finer substrate would also allow for people to keep the sandbed fauna that people want to assist with cleanup and recycling of wastes in the form of food organisms, or just for the novelty of having those different critters. Wouldn't sandbed stirrers also prevent the dead zones since they would stir up finer sands that would break up any clogging.

This is why I was asking about the depth of the bed, and possible use of finer sand substrate.

You stated your opinion that you would use a coarser media, but I don't understand why a shallower bed of finer media would not also be affective. Can't you get water to flow through the bed of finer material? Can't you get the same pressure drop by using smaller holes in the PVC pipe? Or would you need a longer drop for the siphon tube to increase pressure drop through a fine sand bed?


I asked about whether there were solid components to the waste that builds up in the sandbed that we should be concerned with. I don't see this really being addressed in this thread besides you stating that the bacteria should eat everything and it will all be in solution. I think more measurments on the contents of your wastewater, vs what you are adding in the way of food and salt etc should be done. Try to correlate inputs to outputs, that way you will see what is building up possibly in your system. Some things will be incorporated into biomass of fish and corals, but other things are probably still accumulating and filling in your coarse sandbed like any other DSB. The question is... what?

Have you done any sampling of your bed, like a core sample so you can check for accumulating solids and preciptates?

The waste water you are throwing away, is it a higher concentration of heavy metals like copper? Or are these still possibly accumulating in your system so that after a 2 year period, you will have a crash just like DSB? Long term data would help show possible things to be concerned with.

This also relates to why I asked what the actual downfall of DSB really is. I know this has been debated, and some people say it is accumulation of phosphates leading to an algae bloom that consumes oxygen and basically suffocates other inhabitants in the tank. Others say it is accumulation of heavy metals that eventually gets to toxic levels leading to mass die-off. Others think the DSB is not diverse enough or large enough to support enough critters to efficiently recycle materials, leading to buildup and eventual crash of the sandbed.

From reading what you have stated, my interpretation is that you
believe that drawing water off from low in the sandbed will resolve the crashing of DSB, but why? Your proof that your system is working is the lack of rotten-egg smell in the waste water, meaning less hydrogen sulfide in the waste water.

I would like to see more testing over time of what is being drawn
off in your waste water, as well as testing to see if there is
anything still accumulating within your coarser bed.


I asked about possiblities of buildups in the pipes because that is
something that would eventually lead to having to tear down the
system, which would be a complete overhaul of a tank since you
are covering the entire bottom with the PVC tubing.
Since you have different PH in the water that is sitting in the tubes, and then flushing them and filling them with water of a different PH which will sit for hours/days etc, the water parameters will change while the stuff sits in the pipe. Since PH can drop over time, could this lead to salts or other precipitates that will accumulate in the pipe and eventually lead to failure? Again, without long term data to see if the pipes fail over time because of buildup, people are going to be skeptical of claims that your suggestion will fix long term problems with only short term data.


You also state you are using 1/2 pvc with 1/32 inch holes drilled
approximately every 2 inches. The only people I see who made suggestions for orientation of the drain holes in the PVC were Shoestring Reefer and Borecki. Do you drill the holes, on top, bottom, or side of the pvc, or all the way around the circumference of the pipe.


Sorry for the lengthy post, but my questions were not from a lack of reading... lack of understanding yes.

[ddoering]

Another thing that people setting this up should keep in mind.

I noticed that you have suspended your live rock on a platform to elevate it.

This is probably needed to ensure less channeling and dead zones since you dont want your live rock sitting on the sand and blocking water flow through the bed.

I was going to ask about this but saw the pic in the gallery with your liverock on little pvc risers.

Doug

[Shoestring Reefer]

Originally posted by ddoering
This also relates to why I asked what the actual downfall of DSB really is. I know this has been debated, and some people say it is accumulation of phosphates leading to an algae bloom that consumes oxygen and basically suffocates other inhabitants in the tank. Others say it is accumulation of heavy metals that eventually gets to toxic levels leading to mass die-off. Others think the DSB is not diverse enough or large enough to support enough critters to efficiently recycle materials, leading to buildup and eventual crash of the sandbed.
There are many (and long) threads on DSBs, as you must have read (at least partly) based on your post. I've read probably 120 or more pages on DSBs lately, and I get the impression that it's not heavy metals and massive die-offs (not that heavy metals are not a concern) but phosphate problems seem (based on other people's posts) to happen first, and die-off is not often reported.

One suspected cause is that the bacteria fix phosphate, and as the anoxic region moves up through the bed, the aerobic bacteria die and their retaned phosphate is released. This is debatable, but it's the theory that jives with me, FWIW.

[Shoestring Reefer]

Originally posted by ddoering
Your first post states in the description of your tank you are using a 5 inch sandbed of coarser media than usually recommended for a DSB. Later you state it is between 3 and 4 inches.

You state you are using Carib Sea Special Grade Sand, which was later said to be approximately 1 mm (10x coarser than sugar sand).

"Also, remember I do not believe in using fine sugar sand. I believe it is far to dense and leaves little open area to allow adequate fluid flow. I use a very uniform coarse crushed coral that is designed for exactly what I want. Pore space for fluid movement to reach deep into the bed"


My question to this is what is the difference between using a coarser media 5 inches deep, or using a finer media that is perhaps 2 or 3 inches deep?

The smaller particles will provide much greater surface area for bacterial populations than the coarser media, so should improve the biological filtration.

You will not take up as much viewing area in your tank as a 5 or 6 inch bed if you could use a shallower bed with finer particles. You should still get the oxygen depleted areas without needing the same depth, but could prevent the completely oxygen devoid areas by reducing depth of finer grain substrate so it is not a DSB anymore.

Now I don't know about fluid flow, but wouldn't you be able to get adequate fluid flow through a shallower bed? Also, wouldn't a bed of finer particles help combat the channeling of fluid through an area of least resistance? I would think a coarser media would be more likely to channel, since the finer material would settle more and be moved around more by the water flow to fill in any channeling that occurs. You state that detritus will block pores in a finer substrate leading to dead zones. Wouldn't a finer substrate result in detritus being caught higher up in the sandbed in the oxic zone, where bacteria and microfauna can get at it? As opposed to it being sucked down so far into the coarser bed in an anoxic zone etc?

Using the finer substrate would also allow for people to keep the sandbed fauna that people want to assist with cleanup and recycling of wastes in the form of food organisms, or just for the novelty of having those different critters. Wouldn't sandbed stirrers also prevent the dead zones since they would stir up finer sands that would break up any clogging.

This is why I was asking about the depth of the bed, and possible use of finer sand substrate.

You stated your opinion that you would use a coarser media, but I don't understand why a shallower bed of finer media would not also be affective. Can't you get water to flow through the bed of finer material? Can't you get the same pressure drop by using smaller holes in the PVC pipe? Or would you need a longer drop for the siphon tube to increase pressure drop through a fine sand bed?

I'll throw my 0.02 in again, because I'm trying to get 100 posts a week rather than per month, so here goes:

I must agree with ldrhawke that bigger is better. Bigger particles will be less likely to trap detritus in one place; rather, detritus will be more able to simply pass through.

Some of this detritus will be removed from the system, and never get broken down, so IMO more surface area for bacteria is not required. You won't need to break it down, because it's getting flushed out.

[ldrhawke]

Originally posted by ddoering
Hello,

.........Your first post states in the description of your tank you are using a 5 inch sandbed of coarser media than usually recommended for a DSB. Later you state it is between 3 and 4 inches.

...........................You state you are using Carib Sea Special Grade Sand, which was later said to be approximately 1 mm (10x coarser than sugar sand).

..............My question to this is what is the difference between using a coarser media 5 inches deep, or using a finer media that is perhaps 2 or 3 inches deep?

The smaller particles will provide much greater surface area for bacterial populations than the coarser media, so should improve the biological .................................................................................................... ....................... but I don't understand why a shallower bed of finer media would not also be affective. Can't you get water to flow through the bed of finer material? Can't you get the same pressure drop by using smaller holes in the PVC pipe? Or would you need a longer drop for the siphon tube to increase pressure drop through a fine sand bed?


I asked about whether there were solid components to the waste that builds up in the sandbed that we should be concerned with. I don't see this really being addressed in this thread besides you stating that the bacteria should eat everything and it will all be in solution. I think more measurments on the contents of your wastewater, vs what you are adding in the way of food and salt etc should be done. Try to correlate inputs to outputs, that way you will see what is building up possibly in your system. Some things will be incorporated into biomass of fish and corals, but other things are probably still accumulating and filling in your coarse sandbed like any other DSB. The question is... what?

Have you done any sampling of your bed, like a core sample so you can check for accumulating solids and preciptates?

The waste water you are throwing away, is it a higher concentration of heavy metals like copper? Or are these still possibly accumulating in your system so that after a 2 year period, you will have a crash just like DSB? Long term data would help show possible things to be concerned with.

This also relates to why I asked what the actual downfall of DSB really is. I know this has been debated, and some people say it is accumulation of phosphates leading to an algae bloom that consumes oxygen and basically suffocates other inhabitants in the tank. Others say it is accumulation of heavy metals that eventually gets to toxic levels leading to mass die-off. Others think the DSB is not diverse enough or large enough to support enough critters to efficiently recycle materials, leading to buildup and eventual crash of the sandbed.

From reading what you have stated, my interpretation is that you
believe that drawing water off from low in the sandbed will resolve the crashing of DSB, but why? Your proof that your system is working is the lack of rotten-egg smell in the waste water, meaning less hydrogen sulfide in the waste water.

I would like to see more testing over time of what is being drawn
off in your waste water, as well as testing to see if there is
anything still accumulating within your coarser bed.


I asked about possiblities of buildups in the pipes because that is
something that would eventually lead to having to tear down the
system, which would be a complete overhaul of a tank since you
are covering the entire bottom with the PVC tubing.
Since you have different PH in the water that is sitting in the tubes, and then flushing them and filling them with water of a different PH which will sit for hours/days etc, the water parameters will change while the stuff sits in the pipe. Since PH can drop over time, could this lead to salts or other precipitates that will accumulate in the pipe and eventually lead to failure? Again, without long term data to see if the pipes fail over time because of buildup, people are going to be skeptical of claims that your suggestion will fix long term problems with only short term data.


You also state you are using 1/2 pvc with 1/32 inch holes drilled
approximately every 2 inches. The only people I see who made suggestions for orientation of the drain holes in the PVC were Shoestring Reefer and Borecki. Do you drill the holes, on top, bottom, or side of the pvc, or all the way around the circumference of the pipe.


Sorry for the lengthy post, but my questions were not from a lack of reading... lack of understanding yes.

____________________________

Measured 3.5" front and 5" rear.

Carib Sea Special Grade is 1 to 1.7mm. It's listed in their literature.

You have asked a lot of good questions. Many of which you could have answer before asking, or have little real importance, or you know there is no answer for yet, the are what I call the " how high is up questioning approach". Since you read what I have written, you and knew the extent of my testing before even asking the questions.

Not to be a smart a**, but a lot your questions are posed as if I am on your pay roll and you are demanding I prove and verify everything I say, and then report to you. I am just presenting an idea that I think the community can benefit from. I stated numerous times that a lot of testing needs to be done to fine tune the concept of CPW.

Any person so opinionated and able to write such a long dissertation on the high biological value of fine sand should be able to verify and answer a few questions for me, support such an eloquent long list.

Most all of all of your questions are based on your belief that fine sand is better than coarse sand. I like to see some support data for fine sand.

What is the minimum, maximum , and average grain size of the fine sand you purpose? How deep is the fine sand bed? What is the flow rate through your fine sand? What is the pressure drop per inch of depth? At what point and mm size do you consider the fine sand too fine? What is the pore space between the fine sand particles? How long a life to you get before blinding occurs? At what mesh size do you consider your fine sand a clay*? How long have you tested fine sand in the bottom of you tank? Hve you tested it with a plenum underneath? What was your biological loading during the test? Does calcification cause blinding in your fine sand now? Do you think you will have more or less binding with flow through the bed? How do you know you have more active bacteria on fine sand? Have bacteria counts at various depths and over an extended period been done to evaluate life support. At what depth in the fine do you find anoxic conditions? What is the pH at various depths? Have you measure the nitrates and phosphate concentrations in the bottom of your present tank? What is your present set up and how long have you been using it.

Sorry, I don't have all the answers either.


Easy to ask a lot of questions.

These are good questions also. What are your answers? You answer these and then I'll attempt to answer yours.

*Clay is often used as an impermeable ground seal layer for ponds.

[Scleractinian]

Originally posted by Randy Holmes-Farley
The only conflicting views are from people that simply do not want to accept the data below and feel they have some way to improve upon what I have described it takes to build a CPW system to work effectively.

Just a comment here that we will probably address more in the chemistry forum. Note that some of these test kits involve redox chemistry. A little nitrite shows up as a lot of nitrate in some kits, for example. Since the plenum is a reducing situation where there may be redox species like nitrite and sulfite and other things, I tend to worry about the primary data that was generated by Thiel (not a chemist), and is being used to test these systems as well.

I'm very interested in your opinions of the potential merits of the 'process' Randy... I may be oversimplifying, but it seems that, if we can understand what's actually going on and manage it that the 'process' might function as a kind of infinitely deep sandbed...

My questions about automating effluent withdrawls are inspired by the periodic dosing (batch treatment) used in wastewater treatment systems. Do you think that it might be possible to treat a sandbed w/ a plenum and effluent drain as kind of a 'batch reactor' using this 'process', or that a VERY (dropwise) slow, consistent, flow might function like a denitrator coil, but be effective on PO4 as well?

Is anyone familiar with the design and function of small intermittent sand filters (ISF) used for on-site wastewater treatment?

BTW, it's (usually) clay if particle size is less than (about) 2 microns.

[ddoering]

Hi Shoestring,

First let me thank you for actually responding to my questions in regards to DSB and the substrate depth and size.

I had read a lot on DSB and old tank syndrome, and with all the different opinions and theories my head was spinning.

If the main issue with a DSB is phosphate buildup and release as the bed goes anoxic and bacteria dies, and not massive die offs, maybe I will just go with a DSB.

I want to have a lot of grazers and other critters in the tank, which is going to require algae to feed them, so if the problem is not the tank getting nuked and large die-offs, a DSB that lasts a few years before I have to transfer animals and then clean it out doesn't sound too bad. By then I would probably want a bigger tank anyway ;)

I also value your opinion that coarser would be better, but you seem to be taking this approach for a different reason than ldrhawke was proposing.

You think coarser would be better because it would allow you to siphon out the solid wastes, and so they would not need to be processed by the bacteria because they are removed.

This makes sense, and is basically a modified under gravel filter that you are dumping the waste water instead of trying to re-use it after biological filtration. But if you are not depending on the sandbed for biological filtration, does it really matter what depth the sandbed is? In other words, wouldn't a coarse bed of 2 inches be better than a coarse bed of 5 inches if you are just trying to siphon out waste before it is broken down? Less bed to go through, less chance of clogging in the bed etc?

From ldrhawke's description of how this is supposed to work, you want water flow to suck the waste down into the sandbed so that the bacteria can go to work on it, and that the waste water siphoned from the bottom will have all the wastes in higher concentrations and soluble so you can export them.

This is why I don't understand why bed depth would make a difference. I see it how you are describing, which is basically an under gravel filter and vacuuming the detritus from the sandbed, but doing it from the bottom instead of from the top.

If you are actually relying on the biological processing in the bed, and just trying to prevent the deep anoxic area where sulphate reduction or whatever takes place, resulting in buildup of hydrogen sulfide and the anoxic layer moving towards the surface, then I would expect a shallower bed fo finer grain sand might also work.

It would be worth experimenting with, since I already have 10 bags or so of southdown sand that I bought in preparing for setting up a tank.

It will have to wait until I actually move out of this apartment so I can setup my first tank. That is why I am on these boards, trying to learn from other peoples' mistakes and experience :)

Cheers,
Doug

[ddoering]

ldrhawke,

Frankly I find your responses throughout this thread have been very antagonistic. You seem to lash out at anybody who asks a question or does not get down on their knees and bow to your greater wisdom for proposing this filtering method.

I tried to ignore your arrogance, and cocksure attitude to my first post where I was asking questions, and where you just blindly assumed that I had not read the thread. (It's not as if I hadn't had to get past it in some of your previous responses)

When I tried to explain why in detail I had asked the questions to demonstrate that I had indeed read the thread, I get more flippant remarks from you attacking me.

First I didn't read the thread, and my questions could be answered if I only would review the previous posts.

Next my questions are "good questions" but you brush them off as if they were an insult to ask you since I can answer them myself, or because there is no answer to those questions yet.
(You can't have it both ways, they can't be answered by reading the thread, and yet have no answers.) Also, just so you know my personality type, if I knew the answers I wouldn't ask you a question, I would just state that you were full of BS, and would prove it.

Lets clear some things up:

1) You are the person who started this thread, proposing this methodology and getting snooty naming it CPW.

2) You are the one proposing this will fix what is wrong with DSB and prevent crashing.

3) You are the one who stated in the beginning that you don't need long term results to know this will work.

4) You are the one who flamed somebody who was skeptical when stating they wanted more long term data to show the success of this method before they would embrace it as the next holy grail of reefkeeping.

5) You are the one who makes claims to being an expert in this area, with your company doing waste management etc. You even went so far as to put down somebody else who's knowledge in fluid dynamics would far exceed mine. So when I ask a question, it is showing that I am acknowleding you have knowledge and experience that I lack, and I am questioning your method to get a better understanding of how it works. Any idea that can not stand some questioning, and give responses to explain principles underlying the theory should not be presented as you have done, basically stating that what you say is FACT.

I give the idea merit, but nothing is so perfect it can't be improved upon. And if you do not see the benefit of having people with different viewpoints asking questions or making suggestions, why are you posting to this board?

I think your questions in your last post are useful, and would provide a good basis for a methodology for testing different grain sizes in the bed to see if adjusting this improves on the idea you proposed. Oh, and as you are so fond of basically blowing off answers and not giving data, you can find out the distribution of particle size of southdown sand somewhere here on RC. I believe it was a post in Dr. Ron's forum.

As you can clearly read, my hobby experience is just starting, and I don't even have a tank set up yet. This is why I come to these boards, and read, and ask questions. Some of my questions may seem stupid, some may re-ask something you feel you already answered, some may simply be me playing devil's advocate.

As for my motivation asking about smaller grain sand, it is simply that I have already bought some southdown and would like to use it instead of having to pay an overpriced amount at a LFS for specific sand.


Overall, I think the idea has merit, and can probably use some fine tuning/experimenting to see what comes of it to benefit the hobby.

Your attitude can definately use some adjustment. Quit being so defensive and antagonistic when people ask questions etc. If you can't stand people calling your baby ugly, don't enter it in any beauty pageants.

Doug

P.S. I think the naming of this methodology as CPW is pretentious BS, but that is just my opinion.

[Shoestring Reefer]

Originally posted by ddoering

I had read a lot on DSB and old tank syndrome, and with all the different opinions and theories my head was spinning.
I know the feeling.

Originally posted by ddoering

If the main issue with a DSB is phosphate buildup and release as the bed goes anoxic and bacteria dies, and not massive die offs, maybe I will just go with a DSB.

I want to have a lot of grazers and other critters in the tank, which is going to require algae to feed them, so if the problem is not the tank getting nuked and large die-offs, a DSB that lasts a few years before I have to transfer animals and then clean it out doesn't sound too bad. By then I would probably want a bigger tank anyway ;)

Well, they usually seem to last a few years. There's a DSB poll, if you're interested in some very un-scientific statistics. Just remember to vacuum the poop. I have a DSB, but I'm going to have jawfish, so my DSB really won't function as a DSB, anyways. I'll be hopefully getting a house in a year or two (cross fingers) so it will be moved, anyway. I'll probably want a bigger tank, too.

Originally posted by ddoering

I also value your opinion that coarser would be better, but you seem to be taking this approach for a different reason than ldrhawke was proposing.

You think coarser would be better because it would allow you to siphon out the solid wastes, and so they would not need to be processed by the bacteria because they are removed.
Yes, I imagine it functioning differently that ldrhawke proposes. The way I picture it, there is a net flow down through the bed, so not much is going to come up from the bed-certainly not much from the bottom of a deep bed. If that's the case, there won't be much biological filtration for the tank-the filtered water will leave the system. But, if there won't be much biological filtration for the tank, why bother in the first place? I suspect the top-most part of the bed will help with water column filtration, but I wouldn't imagine the bottom of a 5" bed with downward flushing 3 times a day will contribute much.

Originally posted by ddoering

This makes sense, and is basically a modified under gravel filter that you are dumping the waste water instead of trying to re-use it after biological filtration. But if you are not depending on the sandbed for biological filtration, does it really matter what depth the sandbed is? In other words, wouldn't a coarse bed of 2 inches be better than a coarse bed of 5 inches if you are just trying to siphon out waste before it is broken down? Less bed to go through, less chance of clogging in the bed etc?

From ldrhawke's description of how this is supposed to work, you want water flow to suck the waste down into the sandbed so that the bacteria can go to work on it, and that the waste water siphoned from the bottom will have all the wastes in higher concentrations and soluble so you can export them.

This is why I don't understand why bed depth would make a difference. I see it how you are describing, which is basically an under gravel filter and vacuuming the detritus from the sandbed, but doing it from the bottom instead of from the top.

If you are actually relying on the biological processing in the bed, and just trying to prevent the deep anoxic area where sulphate reduction or whatever takes place, resulting in buildup of hydrogen sulfide and the anoxic layer moving towards the surface, then I would expect a shallower bed fo finer grain sand might also work.

Well, I'm not sure. I think that what you say has merit, but I'm just stuck in the DSB mentality, I guess. Deeper just "feels right" to me.
BUT- I'm not setting one up. If you are, just go with your gut. It appears that you will have the second tank set up like this, so you could be a pioneer. Go for what you think is right, and keep us posted.

Originally posted by ddoering

It would be worth experimenting with, since I already have 10 bags or so of southdown sand that I bought in preparing for setting up a tank.

I only bought 3 or 4. The last bag was torn and half-empty (or, half full?) of sand, so I had to scoop it up off the floor. It's a shame that DSBs turned out to not be as great as we all hoped; South Down/Old Castle was a pretty nice find.

Originally posted by ddoering

It will have to wait until I actually move out of this apartment so I can setup my first tank. That is why I am on these boards, trying to learn from other peoples' mistakes and experience :)

Cheers,
Doug
I know the feeling; moving is a pain, and having a tank doesn't make it easier.

[Shoestring Reefer]

Originally posted by ddoering

I give the idea merit, but nothing is so perfect it can't be improved upon.
I agree, and I really enjoy the process. I'd say it's the engineer in me, except that pretty much everyone seems to enjoy it. That's why I've stuck around.

Try to not let anyone here ruin your day. Trust me, I get pretty ticked, too; but then again, there are a lot of great people on here with decades of experience who will spend incredable amounts of time helping us newbes out.

[H20ENG]

Quote by scleractinian:
"Do you think that it might be possible to treat a sandbed w/ a plenum and effluent drain as kind of a 'batch reactor' using this 'process'"
This is the way I think this "method" SHOULD be used if we want to retain the beds ability to denitrify. It is very possible to remove too much water from the bottom and reduce the number of denitrifiers by flushing the bed with oxygenated water. IMO, the flow rate can only be adjusted by testing the effluents DO content, or very gradual changes with consistent nitrate testing of the main tank.
It almost sounds as if ldrhake no longer wishes to use his bed for denitrification, only for nitrification. Cant get a straight answer.... Maybe he can clarify.
Keep up the great commentary, guys! Funny how some of these things get turned into soap operas.
Chris

[ddoering]

Hey Shoestring,

Once I get things setup I will definately be posting to show progress and get feedback, as well as seeing if anybody has ideas on improving things.

It is also good to get an idea of things that you might want to test for, so you can do so from the beginning and keep as accurate of data as you want so others can compare their experience to them. (Part of the reason I was asking about what is building up in the bed... I want to know if it is something
I can test for and should when I get my setup cycled and going).

I try to give people the benefit of the doubt on here, and really do appreciate the help from people who have taken time to answer questions or provide insight on new ideas. From researching and reading on here, I have already probably saved countless fish/corals and money that would have been lost, and I haven't even cycled a tank yet.

Cheers,
Doug

[Randy Holmes-Farley]

I'm not sure what criteria would be useful to show that draining water off of a plenum was a better procedure than a DSB alone, with or without a plenum.

What exactly are you guys proposing to use to say that it is a success?

[ldrhawke]

Originally posted by Randy Holmes-Farley
I'm not sure what criteria would be useful to show that draining water off of a plenum was a better procedure than a DSB alone, with or without a plenum.

What exactly are you guys proposing to use to say that it is a success?

Good question....

I know you are not a big believer in what an ORP meter shows, because there are so many variables and different readings for every tank.

I do believe the changes in ORP read out is indication of good and bad changes in tank chemistry.

The coral and fish appear much happier in a tank with an ORP reading of 350 to 400 compared to one at 200. I also know this is subjective, but my observation and a number of other reef keepers observation agree. Nearly every commercial aquarium uses ozone, and an ORP controller, to raise ORP levels. Many still believe you cannot keep a tank at its best without it. But, that is another topic.;)

Example: When I feed my tank ORP drop 30 or 40 points and then comes back up over the next few hours.

I had been using a declining ORP reading as an indiction if the tank is getting out of balance and water quality is dropping. When making a 15% water change the ORP would move back up and the response to change would happen quicker, than with a low ORP.

To me an ORP reading is like a looking at a barometer for the weather. Doesn't necessarily tell you everything but is a good indicator of change or rate of change.

Back to your point...."what will determine CPW is a success".

As I have posted, my tank experience has been, even with making 15% weekly water changes, to maintain an ORP setting of 350Mv, my ozone feed would cycle all day. When I was wasting only a half quart a day with CPW, ozone would still cycle all day.

When I increased my CPW rate to 1 gallon a day, my ORP stopped cycling. Not only stopped cycling but continued to climb to just under 400mv. It has virtually eliminated the feeding of ozone, which I have set at 350mv on the controller.

I know we can question the value of ORP and what this all means, but to me it is an indication that I am getting positive results.

Before my SPS would not open up and appeared to be struggling. My frog spawn was shrinking. They are now both keep their polyps open all day, appear to be growing, and in general the whole looks much better.

Why do I think CPW is the cause of this? Based on logic and data, waste concentrates in a DSB. CPW removes some of that concentrated waste and reduces the amount that migrates back to the top of the substrate by keeping the flow toward the bottom of the substrate and releasing build up.

How do I know this.....

1.The nitrate and phosphate in the waste is always much higher than what is in the water column.

2. If, instead of dumping the wasting fluid down the drain, I allow it back into the tank, my ORP meter drops over 100 points in a few minutes and takes almost a day to recover.

3. I am wasting only about 1/2 of what I was removing with water changes and getting improved ORP readings without ozone feed.

3. If I drop a few pods or newly hatched brine shrimp into what is being wasted they immediately die.

4. I know I have one more way of measuring and reacting to water quality; other than measuring Ca,Alk,Ph,Ni, Ammonia,etc.etc,etc. in trying to maintain life in a bottle.

It is logical if you remove the waste from where it appears to be concentrating, instead of simply pulling it from the water column, that you will have to remove less.

Chemical and biological chemistry and the what, how, and when is nice to know and understand. It may help you improve results. As more reef tank keepers apply CPW an start to develop more history and data, I am sure we will see further improvements.

The most important thing to me is always results.

As in a lab, sometimes you analysis what you have, even before you know exactly why you have it. Often the physical order of making a reaction is as or more important than the chemicals used. Experimenting with the variables to improve the results is what normally follows.

I think I learned this when I was ten years old watching a movie, in the Museum of Science and Industry in Chicago, about the men and how they discovered aluminum and vulcanized rubber in kitchen labs.;)

[Shoestring Reefer]

Originally posted by Randy Holmes-Farley
I'm not sure what criteria would be useful to show that draining water off of a plenum was a better procedure than a DSB alone, with or without a plenum.

What exactly are you guys proposing to use to say that it is a success?
Good question IMO, Randy. That's not really been discussed, and is a pretty important topic.

Well, long-term success is out, because that can be achieved with either DSB or DSB with plenum, or with BB. Plus, you would need to wait 10 years (assuming it didn't fail before then.)

If my head is on straight, ORP testing of the bed is out, because DSBs are bound to have low orp. Correct me if that's wrong.

Maby ORP testing of the water column, but many people don't even monitor orp; having an OPR of 320 in one system and 360 in another doesn't necessarily one system is a success, the other a failure. Unfortunately, it's one of the few things we can observe.

You can't test the water for phosphate, because macro-algae just suck that up. Nitrite and ammonia should be undetectable unless something really wrong, too.

Maby nitrate in the water column?

Maby a side-by-side comparison of two similar tanks (maby even sharing the same water, to eliminate water quality contributions to bed degeneration) to see which is the first to release phosphate (by waiting for the blooms, and then testing the bed material, possibly sampling at various depths.) Maby, bed testing could be done in the meantime. Obviously, more than my little phosphate test kit would be required, but if a laboratory is what it takes, that's what it takes.

I don't think a test of the waste water really can indicate success, because that water is thrown away. Sort of like testing RO waste water to see if your RO is working properly. It can indicate the performance of the system for tweaking purposes, and maby changes in trended data would indicate potential or impending failure, but I'm not sure.

I guess the problem, as I see it, would be making a controlled experiment, and keeping in mind that success/failure is based on long-term water column quality (because that's what we're after in this hobby) and not bed quality (because the bed is just a tool, not the goal.)

[Shoestring Reefer]

From what I've seen, an ORP meter is about $100.00. If, in addition to that, coarse (ie, not South Down/Old Castle) substrait is required (at $0.50 to $1.00/lb), you're talking about $200 to set up a bed in a 55-gallon tank, not to mention the plumbing.

That puts it out of reach of many beginners, especially considering that 1) a lot of us are in apartments, and will be moving, anyways. and 2) A DSb costs about $20 to set up.

It would be nice if a non-orp way of testing the water could be found, just from a financial standpoint. That would get more nubes trying it sooner, building a bigger pool of reefers with experience.

[H20ENG]

$0.02 more....
One thing to consider, in defense of ldrhawke, is the other methods that were so widely adopted (Plenum, DSB, Wet/Dry, etc.) WITHOUT the testing data we all want to see here. These methods have shown their good and bad after many installations, and this is just another method that may prove to work or not after more use and tweaking by reefers.
I propose that we still dont really have a handle on what really goes on in a tank, though we are getting pretty close.
To say this is the end-all to filtration would be wrong. Even ldrhawke has said that it will require more testing, (though he seems to have most of the answers.....).
At least, its good discussion to further the knowledge of the hobby.

[6 Line]

I would just like to concur with "ddoering"

You have stated on here how "YOUR DESIGN" is such an improvement on the DSB and Plennum designs, to which many people have had great success and many people have had failures.
I for one think that you have just jumped on the back of a system to which there are some technical issues relating to there demise, and started BLOWING YOUR OWN TRUMPET on how fantastic and wonderful you really think you are, because you added a drain off system.
Your system is only a modern day example of what Edward Frankland designed in 1868 after the invention of the Septic Tank by 'Louis Moureas' in 1860 (was not named a Septic Tank until 1895), Edward F added fine sand settlement chambers to allow the efluent from the affore mentioned Septic Tank.

So this brings me to another point you made on how good your company is to give you your so called credibility on this board, You have only benefitted from what the Greeks started in 300B.C.E then passed to the Romans etc. I think they call this Evolution and Knowledge Transitional Developement.

If you give advise, you need to accept criticism or questioning to allow others to Develop there own knowledge, alas you see fit to great peoples questions with contempt and dismiss them as simply not worthy of sensible explinations.

I am with others on this board who take things as they come and share what I have learned with others. I find people like yourself very infuriating due to there own self opinionated thoughts ."Look at me I'm brilliant"

I hate to burst your bubble, but lets wait for your system to see 10 years with no problems to start dictating to others how magnificent you are!!!!

Regards
Jay.

P.S. Us English do like a joke, but we like to be in decent company to appreciatte it.
:bum:

[Shoestring Reefer]

Originally posted by H20ENG
$0.02 more....
I propose that we still dont really have a handle on what really goes on in a tank, though we are getting pretty close.

...

At least, its good discussion to further the knowledge of the hobby.
That sums it up quite nicely. It's a shame we have to wait several years to see if a method panns out or not, though.

[ldrhawke]

Originally posted by H20ENG
Quote by scleractinian:
"Do you think that it might be possible to treat a sandbed w/ a plenum and effluent drain as kind of a 'batch reactor' using this 'process'"
This is the way I think this "method" SHOULD be used if we want to retain the beds ability to denitrify. It is very possible to remove too much water from the bottom and reduce the number of denitrifiers by flushing the bed with oxygenated water. IMO, the flow rate can only be adjusted by testing the effluents DO content, or very gradual changes with consistent nitrate testing of the main tank.
It almost sounds as if ldrhake no longer wishes to use his bed for denitrification, only for nitrification. Cant get a straight answer.... Maybe he can clarify.
Keep up the great commentary, guys! Funny how some of these things get turned into soap operas.
Chris

I thought I have been giving straight answers from the beginning.

I initially hoped and believed a DSB/P system could be set up to complete the nitrate cycle. I no longer believe that based on present experience and knowing about what time and volume is required for de-nitrification. There is not enough volume in a tanks DSP to efficiently complete the nitrification cycles.

Everyone seems to feel just because a nitrification cycles takes place in a DSB that is all there is to it. They totally disregard loading and transfer required to process all the waste in the water column above.

Can you set up separate additional systems to complete they nitrification cycles...certainly. I have said numerous times that can easily be done.

This is not the question you should be asking. These are the questions to ask.

1. Is the cost for de-nitrification equipment and operational oversight worth it compared to simply dumping 1/60th your system volume into the drain?

2. If i did install all the equipment to complete the total nitrification cycle have I totally treated the waste water, or are the other type of waste such as phosphate, silicate, and other organics not fully stabilized that I will be recycling back into the tank?

3. What sort of additional treatment or filters will I have to add on to remove phosphates, silicates, and organics after de-nitrification?

4. Is it easier, cheaper, and more logical to simply look waste a gallon ( or 1/60th) from the plenum?

5. Don't I have to waste even more water with normal water changes anyway?

6. Don't I need to replenish the minor elements used up and put them back into the water, no matter what I do? Isn't is simpler and easier to do it with fresh salt mix than separate costly additives?

I now look at the substrate bed as a large biological dash pot that can absorbs shock loads.

I look at it as a good source of food for the coral.

I will make up for a DSB's biological processing inefficiency in simplest, easiest, and most cost effective manner.....dump 1/60 of my volume every day into the drain.

If you read my past posts I have said this same thing time and time again. Maybe listing it in this manner will make it easier to understand.

[Randy Holmes-Farley]

The reason that I asked about what might demonstrate that plenum draining is a benefit is that there are a host of proposed technologies, from ozone to eco-aqualizers. Knowing that there is a clear benefit from using them is far from trivial.

[Scleractinian]

Originally posted by
I thought I have been giving straight answers from the beginning.

...

If you read my past posts I have said this same thing time and time again. Maybe listing it in this manner will make it easier to understand.

ldrhawke-- Ummm... I should have been more clear in my post (since I'm VERY sure that you must have READ it), but my last questions above were intended for Randy, and for anyone familiar w/ small scale ISF technology.

The tone of your responses is what leads others to post in a way that you seem to find disrespectful. This thread is not yours. WADR, you seem to feel that those who question, critique, propose potential improvements to, etc. your concept are personally attacking you. I might suggest that this is not the case, that you lighten up a bit, and that you realize and accept that RC is a FORUM, intended for the polite exchange of ideas.

If you'd prefer that people not be skeptical of your idea, or that they achieve a level of enlightenment approaching yours before they post questions, then perhaps you should host your own discussion elsewhere...

I appreciate the fact that you posted the idea here, and resepect your efforts in trying to help people understand it better, but...

Remember, I am an idiot, not an engineer or CEO, and am probably a Greenie and an EPA type, who apparently can't read. ;)

[Scleractinian]

Originally posted by Randy Holmes-Farley
I'm not sure what criteria would be useful to show that draining water off of a plenum was a better procedure than a DSB alone, with or without a plenum.

What exactly are you guys proposing to use to say that it is a success?

The barebottom crowd seems to be suggesting that conventional (ala Shimek) DSBs have some undefined crisis at around year 4.

Got 5 years?

Randy, if PO4 accumulation and release is supposed to be the problem w/ aging sandbeds, is there a practical way for us to compare PO4 inputs (food and water) and exports (skimmer, water changes, and especially CPW (TM) ;) effluent, etc.?

[Randy Holmes-Farley]

Randy, if PO4 accumulation and release is supposed to be the problem w/ aging sandbeds, is there a practical way for us to compare PO4 inputs (food and water) and exports (skimmer, water changes, and especially CPW (TM) effluent, etc

I'd think you would be comparing two large numbers (input and output), looking to see if the small difference between them got bigger or smaller. Given the difficulties of measuring phosphorus in things like solid macroalgae, skimmate, coral skeletons, and fish growth, I don't think it would be doable.

[Randy Holmes-Farley]

Do you think that it might be possible to treat a sandbed w/ a plenum and effluent drain as kind of a 'batch reactor' using this 'process', or that a VERY (dropwise) slow, consistent, flow might function like a denitrator coil, but be effective on PO4 as well?

Yes, that seems possible. I'm not sure how you'd decide what spped or frequency of draining was optimal. Maybe an ORP electrode stuck into the plenum, drain when it hits a certain low ORP threshold, and stop when it hits a higher threshold.

That would keep the plenum from getting too anoxic (if, indeed, that typically happens) and also prevent it from becoming too oxic, shutting down anoxic processes until the oxygen is depleted again.

[Scleractinian]

Originally posted by Randy Holmes-Farley
Do you think that it might be possible to treat a sandbed w/ a plenum and effluent drain as kind of a 'batch reactor' using this 'process', or that a VERY (dropwise) slow, consistent, flow might function like a denitrator coil, but be effective on PO4 as well?

Yes, that seems possible. I'm not sure how you'd decide what spped or frequency of draining was optimal. Maybe an ORP electrode stuck into the plenum, drain when it hits a certain low ORP threshold, and stop when it hits a higher threshold.

That would keep the plenum from getting too anoxic (if, indeed, that typically happens) and also prevent it from becoming too oxic, shutting down anoxic processes until the oxygen is depleted again.

Can you think of anyone familiar enough w/ the chemistry and microecology of marine sediments (and w/ an interest in captive reefs, of course) to offer guidance on such a thing?

When I was at the FSU lab at Sopchoppy, we used to make fun of the geeks and their Winogradsky Columns... guess I should have paid more attention to what was IN the sand, and not just on how much of it was moving where.

[BORECKI]

I want to backtrack a bit to the subject of compacting the sand bed and "chanelling".
At first I sugested using a eggcrate to install a pleniun under the DSB only to simplify the construction of the aperatus versus constructing a maze of pipes w/ holes each individualy capped with a small patch of fabric.
The responce I got was that because of the low head pressure anf flow there is no way to have even flow through all the sand bed and that places that by chance would get less flow would clog and force chanelling in other spots.
This is true
BUT ; The exact same thing will happen to a DSB served by a maze of pipes also. Only that in the latter the dead spots will be at the mid points between the holes. Each and every set of two holes will cause a dead spot to form at the mid point!
The only difference is that with a plenium one can fork the DSB to fluff it up easier than between the pipes.
Also ; If any one hole ever clogs up the two dead spots will merge and grow in size with no indication that anything is wrong!
If the whole idea is to revove phosphates than maybe the better option is still a DSB over a plenium where one can simply remove part of the sand every year or two in stages so that in time the whole bed is replaced. Another thing that was touched upon was the possability of the under sand pipes clogging due to lower pH in the stagnent water. That sounds like a possasble maintenence issue.
Boris.

[Shoestring Reefer]

Ok, for those who didn't see it, here is a VERY sucessful tank:

http://reefcentral.com/forums/showthread.php?s=&threadid=284686&highlight=Paul+B+30+Year+Old

[Scleractinian]

Originally posted by BORECKI
I want to backtrack a bit to the subject of compacting the sand bed and "chanelling".
At first I sugested using a eggcrate to install a pleniun under the DSB only to simplify the construction of the aperatus versus constructing a maze of pipes w/ holes each individualy capped with a small patch of fabric.
The responce I got was that because of the low head pressure anf flow there is no way to have even flow through all the sand bed and that places that by chance would get less flow would clog and force chanelling in other spots.
This is true
BUT ; The exact same thing will happen to a DSB served by a maze of pipes also. Only that in the latter the dead spots will be at the mid points between the holes. Each and every set of two holes will cause a dead spot to form at the mid point!
The only difference is that with a plenium one can fork the DSB to fluff it up easier than between the pipes.
Also ; If any one hole ever clogs up the two dead spots will merge and grow in size with no indication that anything is wrong!
If the whole idea is to revove phosphates than maybe the better option is still a DSB over a plenium where one can simply remove part of the sand every year or two in stages so that in time the whole bed is replaced. Another thing that was touched upon was the possability of the under sand pipes clogging due to lower pH in the stagnent water. That sounds like a possasble maintenence issue.
Boris.

This is why I dind't really like the pipe idea. :(

I realize that what I've been wondering about (a drilled plate, elevated off the tank bottom and seaed to the tank sides, w/ a simple drain from the plenum space, rather than from a network of pipes) doesn't fit either the Borecki (TM) or the CPW(TM!!!) ;) model, but at this point I'm really more curious about the biology and chemistry than the plumbing. :)

Besides, at the flows I'm considering trying, plumbing won't matter much... I hope.

Hey!! I've invented my own process and apparatus! It's called the "Discrete Plenum with Drain", or DPD!

[BigDaddy]

I am in the midst of planning my new 280 reef and I have been debating the DSB, BB issue. This might be a nice solution. I hate the look of a BB tank, and I'm concerned about a possible nutrient sink in a DSB. I will continue to follow this closely, thanks for the thoughtful replies.

[Alfalfameister]

First of all, I like the idea of CPW a lot. I have been reading about DSBs, and all the pros and cons about DSBs. The pros were great, but the cons were scary. Especially the hyphothesis that after 2...3... 4 years, the 'garbage can will be full'.

But ldrhawk says his system is improving, but could it be just from CPW? Scott Fellman in www.wetwebmedia.com said something about a regular water change (5% water change, 2x a week).

Since ldrhawk is wasting 1 gallon a day, then he is actually doing 1 gallon a day water changes.

I believe that the best place to change the water would be the water that is the "worst"... which is exactly what the CPW accomplishes.

My question (hyphothetical) is... if ldrhawk changed water at one gallon per day, not via the CPW, wouldn't the water quality improve a lot as well?

I am not debunking CPW. In fact, I think it is the best way to do a water change. I am just pointing out that maybe it's the daily water change that is really improving the water quality (and apparently, the best way to make a water change is via the CPW).

--Alf

[Aged Salt]

Boris, yup, IME, eventually channeling WILL occur. If only back-flushing, areas of clumping in the bed will happen,irregardless of water changes,Bob

[Randy Holmes-Farley]

an you think of anyone familiar enough w/ the chemistry and microecology of marine sediments (and w/ an interest in captive reefs, of course) to offer guidance on such a thing?

Perhaps Ron Shimek.

[wld1783]

WOW at lot of thought here.

I will be moving in a year and using this move as a perfect opportunity to improve my current system.

I've read a lot of posts and it seems that a DSB has advantages but are also prone to crash. ldrhawke has a great idea for those who do not have the luxury of having a separate DSB Refrigium. Like investing money or combat, its a good idea and risk management that wins in the long run. This idea has low risk and I'm looking forward to future results.

For my system I'm still considering a DSB plenum refugium with a periodic drain on the plenum to remove the nasty stuff. For me this is low risk because it will be separate from the main system and can be removed/changed in the future if it becomes a problem.


Bill

[Shoestring Reefer]

Perhapse a different bed (not just grain size) would help, as well. The thread I linked to above is about a 30-year old tank with dolmite gravel.

Any other bed material thoughts?

[red rover]

ldrhawk....

Any updates?

[salt lick]

First a hats off to the CEO of Sewage for sharing his ideas. I think that removing the sulpher and acid from a potentially incomplete organic proccess is good thinking.

My first impression was that I had found balance in 'the Force'. I was following the thread thinking my new 225 gal will use this latest and greatest (400 lbs of southdown is waiting in the game room).

Do I DSB? BB? CPW? Oh the frustration! 10 yrs ago I had 2" of crushed coral in my 110 gallon reef, but removed it on the advice of Julian Sprung (FAMA). He said it was the cause of my algea blooms/ phosphate.

My next thought was that CPW is just doing a 30 gal/month water change on a system that holds 30 gallons (see below).
My estimate of total system volume is 30 gallons (does not take into account glass thickness). Actualy with dillution (1 gallon a day) its more like a 43% water exchange per month!

45 g tank (15" tall) with 5" sand 40 lbs rock and a 15 gal fuge:
tank (+45)
sand is about 10 gal, (-10)
rock/livestock is 15 gal, (-15)
15 gal fuge/sump/ half full is 8 gal (+8)
misc skimmer reactors (+2)

total vol = 30 gallons

The CPW method loses efficiency because of dilution but gains enormously by removing the worst byproduct water from the plenum. Then it struck me as just vaccuming the gravel bed from the bottom (dont know if thats better or not). It seems the CPW is a great way to do water change maintenance.

My next thought is Im not thrilled with a plenum contraption under the sand.

P.S. Please dont call me or my RC buddies idiots. Check your ego at the portal.

:D

[Hawk72]

salt lick,

Where did you get 400 lbs. of southdown in Tehachapi?

The best option is to do what makes sense to you. This hobby is constantly changing. There is noway to say one method is better than the other (DSB,BB,CPW...). When I set mine up next month I am using a plenum with the wasting. I think that combines the best options for myself.

Jason

[llpoolej]

ldrhawke, I think it is a pretty cool idea. A french drain under the sand sucking out the nasty stuff. I agree with the larger size of the sand. Especially with your theories on it.

[DougSupreme]

I guess my main question is how to adopt this method. Is it simply to fill the bottom of your tank with as much piping as possible to evenly draw out the 'Liquor'? then it is simply a matter of siphoning out over the top of the tank? This sounds simple enough, my only concern is that I have about 300# of SD that i planned on using for my bed. Will this work ,or is the particle size too small? would frequent back flushing solve any compacting problems?

[ldrhawke]

Originally posted by red rover
ldrhawk....

Any updates?

Everything is very stable. I did run into one upsetting snag and error on my own part. My ORP probe was giving some high false read outs because it was dirty. When I soaked it in vinegar the ORP dropped almost 50 points, which was disappointing because now I am reading in the low and not the high 300's.

All of the ORP trend affects from my CPW are the same, I am just starting finishing lower than I figured. ORP has stabilized in the 320mv range.

I am going to do a 15% water change to see what if any affect it has on raising the ORP significantly over what I presently read. If it does raise ORP, it may be an indiction I should increase my present wasting rate. If it does not raise ORP it tells me water changes through CPW are about what they should be.

Lesson: If you are using an ORP meter, soak the probe in vinegar at least every few weeks. They will drift high if you don't.

[ldrhawke]

Originally posted by salt lick
First a hats off to the CEO of Sewage for sharing his ideas. I think that removing the sulpher and acid from a potentially incomplete organic proccess is good thinking.

THANKS.......

My first impression was that I had found balance in 'the Force'. I was following the thread thinking my new 225 gal will use this latest and greatest (400 lbs of southdown is waiting in the game room).

Do I DSB? BB? CPW? Oh the frustration! 10 yrs ago I had 2" of crushed coral in my 110 gallon reef, but removed it on the advice of Julian Sprung (FAMA). He said it was the cause of my algea blooms/ phosphate.

.........THE SUBSTRATE DOES COLLECT PHOSPHATE. IT DOESN'T MAKE IT. HOPEFULLY CPW CAN CONTROL ITS BUILD UP AND USE IT AS A CONCENTRATOR POINT TO OUR ADVANTAGE. I DON'T HAVE ALL THE ANSWERS. I DO THINK CPW PUTS US ON THE RIGHT TRACK. TIME WILL TELL...........

My next thought was that CPW is just doing a 30 gal/month water change on a system that holds 30 gallons (see below).
My estimate of total system volume is 30 gallons (does not take into account glass thickness). Actualy with dillution (1 gallon a day) its more like a 43% water exchange per month!

45 g tank (15" tall) with 5" sand 40 lbs rock and a 15 gal fuge:
tank (+45)
sand is about 10 gal, (-10)
rock/livestock is 15 gal, (-15)
15 gal fuge/sump/ half full is 8 gal (+8)
misc skimmer reactors (+2)

total vol = 30 gallons

........SORRY DON'T FOLLOW ALL THE NUMBERS OR WHAT THE QUESTION IS?......

The CPW method loses efficiency because of dilution but gains enormously by removing the worst byproduct water from the plenum. Then it struck me as just vaccuming the gravel bed from the bottom (dont know if thats better or not). It seems the CPW is a great way to do water change maintenance.

My next thought is Im not thrilled with a plenum contraption under the sand.

P.S. Please dont call me or my RC buddies idiots. Check your ego at the portal.

.......IS THERE ANOTHER QUESTION HERE IDIOT?.......:lol:


........JUST KIDDING COULDN'T RESIST... ;)



:D

[ldrhawke]

Originally posted by DougSupreme
I guess my main question is how to adopt this method. Is it simply to fill the bottom of your tank with as much piping as possible to evenly draw out the 'Liquor'? then it is simply a matter of siphoning out over the top of the tank? This sounds simple enough, my only concern is that I have about 300# of SD that i planned on using for my bed. Will this work ,or is the particle size too small? would frequent back flushing solve any compacting problems?

I would be concerned about using sugar sand. I believe it will plug and blind too easily, and cause maldistibution. That is not to say a finer grade filter cloth and shallower depth cannot be used to make it work. As more people use the CPW concept we may find modified different approaches will work, an possibly work better. At this point I believe a coarse grade agaronite is a safer approach.

[aqua_obs]

I've gone through some of what is happening here and hope "The Grand Poobah of Sewage" will lead us to a final answer! I say I've been on some of this path because I decomissioned an undergravel filter which used crushed coral. I decomissioned it because I had a hair algae problem. I thought I could do water changes from this spot because the UGF was built from a PVC network under a grating with window screen. I figured I'd get some of the nasty stuff out. My first water change smelled of elderberry wine (sulfur). That was over the summer and after performing this water change effort a few times I no longer get the sulfur smell. Maybe I've killed off the nitrate eating bacteria by pulling 5 gallons from a 60 gallon tank through the thin gravel bed. Nitrates seem to climb now every week despite a refugium with macro. I worry drlhawk that it is possible to reduce the number of nitrate eating bacteria through the bed by doing more and larger water changes? I'm currently going with your pint change method to see if my corals perk up. Again the sulfur smell has left my water as well, but I wonder if it ever comes back? In my tank, everything was doing really well after the under gravel water changes, but now the last few months things are going down hill and I'm not certain why. Additional point is my crush coral is only 1-1.5 inches thick. My CPW like method has been substantially different. I bet it's a good method, but like others, not a be all end all.

As a second suggestion to people who read RC and email. Don't read emotion into postings as it is usually a reflection more of your own state of mind more than the other persons.

Please keep up the good work dr-Hawk and others! thanks and one love brothers/ two loves for sisters!

:D

[jrm01]

Brett & Chris,

I believe you are thinking of Tom Miller. He wrote a number of articles for MFM back in the late 90's one of which was titled "How To Set Up a Plenum and Plenum Siphon Network to Start a Handy Reef". It is in the April 1998 issue of MFM for those of you interested in taking a look at his thoughts.

Jeff

[H20ENG]

Thanks jrm01!
I knew it wasnt Tom Frakes, but couldnt remember a simple name like Miller :D
IIRC, He had the same general opinion that the plenum goes sour and is a nutrient sink. He didnt waste nearly what ldrhawke does, though. I bet he kept his nitrate reducers happy, though.

ldrhawke,
It seems you dont mind the nitrate reducers being over run with aerobic bacteria due to the volume of your water changes. Do you expect, or have you experienced, that the nitrates will stay very low with water changes only?
Chris

[ldrhawke]

Originally posted by H20ENG
Thanks jrm01!
I knew it wasnt Tom Frakes, but couldnt remember a simple name like Miller :D
IIRC, He had the same general opinion that the plenum goes sour and is a nutrient sink. He didnt waste nearly what ldrhawke does, though. I bet he kept his nitrate reducers happy, though.

ldrhawke,
It seems you don't mind the nitrate reducers being over run with aerobic bacteria due to the volume of your water changes. Do you expect, or have you experienced, that the nitrates will stay very low with water changes only?
Chris

Maybe you or someone else can explain something to me.....what makes people believe, even if you have some de-nitrification taking place below a couple of inches of the bed surface , that you have adequate water exchange rates between the water column above and that lower dead zone, to have any affect on reducing nitrates in the water column?:confused:

I have read theories about how the bugs and osmosis cause turn over in the bottom of a DSB, but I haven't seen any data to substantiate the theory. Can anyone produce data that proves there is an adequate rate of water turn over in the denitrification zone taking place to have any sustantial affect on the water column above. :rolleye1: I could put a capped bottle of waste in the bottom of the tank and it could produce denitrifying bacteria, but unless you have fluid being exchanged it has no affect on anything.

Or to give another example and ask a question: I could build a denitrification coil and remove the waste from CPW and feed it through the coil to denitrify. Even if I put a very small volume coil and only fed it at very low rates, it would be denitrifying. How large a denitrifying coil would you say had to be installed to keep nitrates from building up in the tank? It's physical volume and the allowable flow to maintain denitrifying bacteria will determine it how well it works or if it works at all.:eek1:

I do believe there is denitrifying bacteria, along with sulphide bacteria in the bottom of any tank substrate, but I have yet to see anything that proves there is any realistic rate of fluid exchange, between it and the water column above, to have a positive affect on the tank water. :(

What I have been baffled by is that alot of people blindly accept this exchange is happening, with out proof or even logic to support it.:confused: But they question CPW that is at least producing numbers and data.

Plus, as I have said before, with the CPW concept you really don't care if you have denitrification taking place or not in the substrate. The concept is to physically remove the nitrates, phosphates, and other organic waste being produced or introduced; and keeping a positive flow into and out of the bed and not allow the waste from flowing back into the water column. ;)

[H20ENG]

"Can anyone produce data that proves there is an adequate rate of water turn over in the denitrification zone taking place to have any sustantial affect on the water column above."
A whole bunch of DSB'd tanks that maintain near zero nitrates would tend to be convincing. What is your explination for such denitrification if not the sand bed? Why does installing a DSB drop the nitrates, even though there is no forced exchange of the water?
I was not at all rude or condescending, I am just curious what your nitrate levels are now that you use this method of water changes.
"with the CPW concept you really don't care if you have denitrification taking place or not in the substrate. The concept is to physically remove the nitrates, phosphates, and other organic waste being produced"
Thank you. What were your previous levels of nitrate and what are they now?
You can just answer the question. No one will flame you, Honest!

[Randy Holmes-Farley]

Maybe you or someone else can explain something to me.....what makes people believe, even if you have some de-nitrification taking place below a couple of inches of the bed surface , that you have adequate water exchange rates between the water column above and that lower dead zone, to have any affect on reducing nitrates in the water column?

Regardless of how exactly the nitrate gets into those regions, it clearly happens. It has been demonstrated counless times when folks have added a DSB and found that nitrate levels in their established aquaria dropped from some elevated level (say, 5+ ppm) to less than 1 ppm. The same does not happen with a 1/2" sand bed.

[ldrhawke]

I was not at all rude or condescending, I am just curious what your nitrate levels are now that you use this method of water changes.
"with the CPW concept you really don't care if you have denitrification taking place or not in the substrate. The concept is to physically remove the nitrates, phosphates, and other organic waste being produced"
Thank you. What were your previous levels of nitrate and what are they now?
You can just answer the question. No one will flame you, Honest

My response was not meant to be either neither. That is why I used all the smiley faces. I was and still am curious.

Sorry I didn't answer your question.

My nitrates and phosphates are still non- detectable. Obviously there is something, but it is below the minimum of the test.

Also, regarding the 15% water change I did several days ago, in addition to the daily 1g of CPW, to see if I could improve and increase my ORP mv reading above the 325mv reading it showed. I had a very minor increase to about 335mv and then it dropped back down to the same 325mv range. It appears for my system the 1g per day wasting through the plenum is keeping the system stabile.

I still have some hair algae, but it has stopped growing and the clean up crew is working on the few small tuffs left near the top of the coral structure and light. That may never go completely away because it is so close to the light, a few inches, and the area always catches a little uneaten food before it goes over the overflow.

Regarding Randy's statement Regardless of how exactly the nitrate gets into those regions, it clearly happens. It has been demonstrated countless times when folks have added a DSB and found that nitrate levels in their established aquarium dropped from some elevated level (say, 5+ ppm) to less than 1 ppm. The same does not happen with a 1/2" sand bed.

I believe very very low rates of denitrification is probably happening in a DSB, but I will bet the reef keepers that are also doing that good a job of husbandry in keeping the nitrates below 5ppm and the tester would have a difficult time saying they had a low reading because of not over feeding while they are doing the testing or if it was becasue of the DSB.

I still contend a DSB is a poorly designed and inefficient denitrification system at best. If it is doing minor denitrification it is not doing it very effectively. You have little or no control and a dozen ways to upset it.

Again, a question. At what depth do people feel that in a DSB, for all measurable purposes, it stops processing of waste?

Or to say it another way, at what depth do you feel you no longer get any measurable exchange of fluid and it is a dead zone? Is it 2", 5", 12"? At some point you are not getting any exchange or reintroduction of fresh food for either the oxic or anoxic microbes. At some depth, any additional sand added, has little or no significance in the biological process. What is that magic number?

And the next question. Is it logical to believe that if you positively transport food into those zones, that you can activate them into becoming an oxic or anoxic biological filter?

In contrast to a lot of peoples concern that a CPW system may stop or disrupt denitrification, I believe the odds are just as good, that it reactivates the whole bed depth into becoming more efficient oxic and anoxic biological filters by transporting waste into the full bed depth.

[ldrhawke]

Let me add another comment about my tank, that I feel adds some signifigance to my near zero nitrates and phosphates, my biological loading.

As much as I wanted it to be a reef tank and not fish tank, I am weak when I walk through the LFS and can't pass up an orphan. My tank is far too over loaded by good reef tank standards, but it is still maintaining near zero nitrates and phosphates.

In my 60g system, less gravel and rock space, I have a dozen fish. A Yellow tang, (3) Ocellaris Clown fish, (2) Cardinalfish, Algae Blennyfish, neon goby, (2)yellow headed jawfish, madarinfish, and a spotted madarinfish. I have seen reef tanks on the list tanks 10 times my size with less fish. With the amount of fish waste produced and excess food from feeding, keeping nitrates and phosphates down isn't easy.

I think you have to agree my set up, good or bad, is a good test for the CPW concept and the near zero nitrates and phosphates it has contributed in maintaining.

I say CPW contributes because I strongly believe like others that you should use every gadget you can to maintain water quality. I use a skimmer, filter media, and ozone also.

[Shoestring Reefer]

ldrhawke,

Have your jawfish built burrows? If so, do you feel they have affected the performance of your system?

[H20ENG]

I still contend a DSB is a poorly designed and inefficient denitrification system at best. If it is doing minor denitrification it is not doing it very effectively. You have little or no control and a dozen ways to upset it.

I totally agree. I have always believed that if you have ANY sulfide lurking below the bed, its gone too far anerobic. I dont think there is ANY place in a tank that can safely contain H2S.
And I also agree with you that there are many ways to upset a DSB.
I cannot answer what a perfect depth or grain size is, as there are far too many variables in each system.

[Clay Glover]

LDRHawke,

Thanks for sharing your ideas, experience, and expertise with us fellow reefers. I've read this thread and find your CPW approach worth trying and will apply it to my next tank. If long term disadvantages to using it do eventually come, they are easily remedied by discontinued use.

I have a question that you may be able to help me with. What are the potential disadvantages of using the plenum drain for higher volume, more traditional-type water changes of, say for example, 10% total system volume on a bi-weekly basis versus the smaller, but more frequent, 1/60th daily exchange you currently perform? I assume there are potential advantages to doing small, frequent drainings versus large, less frequent drainings, otherwise why would you do it this way, no? :)

If I understand you correctly, utilizing the DSB for bacterial denitrification is not a primary concern using the CPW approach. Maybe someone can advise me whether upon drainage, would newly introduced O2 into the bed kill denitrifying bacteria? Or just "de-activate" them until anoxic conditions are returned?

Thanks for your time.

[ldrhawke]

Originally posted by Clay Glover
LDRHawke,

Thanks for sharing your ideas, experience, and expertise with us fellow reefers. I've read this thread and find your CPW approach worth trying and will apply it to my next tank. If long term disadvantages to using it do eventually come, they are easily remedied by discontinued use.

I have a question that you may be able to help me with. What are the potential disadvantages of using the plenum drain for higher volume, more traditional-type water changes of, say for example, 10% total system volume on a bi-weekly basis versus the smaller, but more frequent, 1/60th daily exchange you currently perform? I assume there are potential advantages to doing small, frequent drainings versus large, less frequent drainings, otherwise why would you do it this way, no? :)

If I understand you correctly, utilizing the DSB for bacterial denitrification is not a primary concern using the CPW approach. Maybe you can advise me whether upon drainage, does newly introduced O2 into the bed kill denitrifying bacteria? Or just "de-activate" them until anoxic conditions are returned?

Thanks for your time.

You're welcome....Your question as to frequency of change and concern for upsetting the oxic and anoxic bacteria in the bed go hand and hand.

The answer as too how frequent or infrequent you should drain the bed is based on a logical assumption that small frequent changes are better than larger more upsetting changes. On the other hand too small a drainage rate and the potential for a non-flushing action and uneven movement of fluid through the bed increases with low flushing rates. My flushing a pint every 6 hours is an attempt to maintain a flushing action and reverse flood the bed. Can it be done once a day at 4 times the rate and still work....probably.

Can it simply be used for weekly water changes..yes. But now you are disrupting the anoxic zone even more. Will it kill all the anoxic bacteria?..no. It will slow it down but will not kill it all. There is no way to get a uniform enough flow through the bed that can reach all the anoxic bacteria in a short duration flush. It will quickly re-establish itself.

The optimum rate and frequency will vary from system to system. There is a lot we don't know yet as to optimum mode of operation. It may be that weekly 10% flushing works better than uniform daily.

There are other aspects that have yet to be explored. As example: There may be some benefits to low flushing rates because they allow a drop in pH and help to keep and put back into solution phosphates building up in the bed. A lot more testing an monitoring needs to be done to maximize the potential benefits of CPW.

Good questions.....

[Randy Holmes-Farley]

I believe very very low rates of denitrification is probably happening in a DSB, but I will bet the reef keepers that are also doing that good a job of husbandry in keeping the nitrates below 5ppm and the tester would have a difficult time saying they had a low reading because of not over feeding while they are doing the testing or if it was becasue of the DSB.

Well, I disagree, and I think it is quite clear. Before DSB's became popular, many advanced aquarists had elevated nitrate. Most did, in fact, unless they resorted to denitrators or other schemes. When they added DSB's, the nitrate declined, ushering in the era of very low nitrate levels.

That's the only reason they became so popular: because the effect was fairly clear in many cases.

The thickenss required is a strong function of the grain size, IMO.

[darrellh]

ldrhawke,

How long does it take you to remove one pint with your siphon method? When I set up my new 90gal with a CPW bed, I'll use a powerhead with a variable onstriction valve on the disharge side to vary the flow rate. I was also able to find a digital AC timer with 1 sec resolution on E-bay, but unfortunelately I don't see any more available now. I think they were leftover timers from some other OEM project.

One other question. How do you balance the saltwater added and removed for CPW vs the freshwater make up for evaporation? Do you have any tricks for keeping the salinity automatically balanced?

Thanks,
Darrell

[ldrhawke]

Originally posted by Randy Holmes-Farley
I believe very very low rates of denitrification is probably happening in a DSB, but I will bet the reef keepers that are also doing that good a job of husbandry in keeping the nitrates below 5ppm and the tester would have a difficult time saying they had a low reading because of not over feeding while they are doing the testing or if it was becasue of the DSB.

Well, I disagree, and I think it is quite clear. Before DSB's became popular, many advanced aquarists had elevated nitrate. Most did, in fact, unless they resorted to denitrators or other schemes. When they added DSB's, the nitrate declined, ushering in the era of very low nitrate levels.

That's the only reason they became so popular: because the effect was fairly clear in many cases.

The thickenss required is a strong function of the grain size, IMO.

Randy,

As you know I respect your opinion. You been involved in reef keeping for a lot longer than I have. You are one of the best versed and have written technical papers that have become the bible of our hobby.

I don't disagree a DSB denitrifies. I don't disagree with the fact that substrate makes a good biological filter material and at some depth it becomes and anoxic biological filter. I have also read reports stating anoxic conditions can develop close as an inch of the surface in very fine sand and mud.

I am simply questioning, the belief of some that deep is good and deeper is even better. I question at what point beyond a couple of inches of substrate do you have usesless dead space that is of little good and potential harmful.

The whole concept of CPW is to take better advantage of the biological filtering ability of substrate and hopefully improve upon it's efficiency. In doing so, maybe even address the problem that many have experienced with what appears to be a limited life of the normal DSB, which even the most avid past proponents now appear to believe exists.

I believe the more biological filter surface we have in a tank the better.....as long as it can be controlled to some degree and doesn't end up as an anoxic garbage that can get out of control and burp poison back into the tank killing the coral.

My discussing the weakness in the conventional DSB concept doesn't mean I am against DSB's. I'm only adding a new twist by adding a degree of control and actually trying to salvage the DSB biofilter concept that appears to be on a down hill slide .;)

[ldrhawke]

Originally posted by darrellh
ldrhawke,

How long does it take you to remove one pint with your siphon method? When I set up my new 90gal with a CPW bed, I'll use a powerhead with a variable onstriction valve on the disharge side to vary the flow rate. I was also able to find a digital AC timer with 1 sec resolution on E-bay, but unfortunelately I don't see any more available now. I think they were leftover timers from some other OEM project.

One other question. How do you balance the saltwater added and removed for CPW vs the freshwater make up for evaporation? Do you have any tricks for keeping the salinity automatically balanced?

Thanks,
Darrell

Darrell, Darrell, and your Brother Darrell....:p

I have it partially valved off and it takes about a minutes to remove a pint in my system.

The power head should work fine. Just make sure you put a syphon break at the top to keep it from draining all the water.

My fresh water make up is done with a float valve which opens the RO/DI line to the sump. The water drips in. NO SALT is required for the evaported water.

For the CPW drain I add about 1/2 cup of salt every day, a cup a couple of days, for every gallon I remove. I think doing water changes in this manner also helps to reduce shock to sensative coral that you can get with larger quantity water changes. I check SG regularly with a refractometer.

[darrellh]

Hi ldrhawke,

Nice, but there are (were) only two Darrells..the third guy was Larry. Do you really think their mom was that stupid to name all three Darrell.

My concern with removing/adding saltwater with an automated setup is that it will be hard to match the volume removed vs added. If this is always out of whack in the same direction, then the SG will eventually rise or fall. I realize I can monitor the SG of the tank manully and then adjust things accordingly, but I want to automate this as much as possible.

Thanks,
Darrell

[ldrhawke]

Originally posted by darrellh
Hi ldrhawke,

Nice, but there are (were) only two Darrells..the third guy was Larry. Do you really think their mom was that stupid to name all three Darrell.

My concern with removing/adding saltwater with an automated setup is that it will be hard to match the volume removed vs added. If this is always out of whack in the same direction, then the SG will eventually rise or fall. I realize I can monitor the SG of the tank manully and then adjust things accordingly, but I want to automate this as much as possible.

Thanks,
Darrell

Just be thank full your mom didn't name you George. ie; George Foreman...:p

Without adding a controller for measuring and automatically adding concentrated salt solution, you simply need to be creative.

How's this for a Rube set up, if you have the space or a fish room. Get a large plastic container and pipe it to over flow into you fuge. Use the container for make up of fresh salt mix. Then take a heavy duty plastic garbage bag and discharge you CPW into it. Put the garbage bag in the fresh salt mix container.

Now as the tank is wasted it displaces the same amount right back into the tank.
:rollface:

If the fresh make up container is a 55 g drum, you will only need to make up a fresh salt mix once every couple of months.

Rube would love it.....:mixed:

[Randy Holmes-Farley]

I am simply questioning, the belief of some that deep is good and deeper is even better. I question at what point beyond a couple of inches of substrate do you have usesless dead space that is of little good and potential harmful.


OK, that's a reasonable question. Many of the reefkeepers that have added deep sand over the years (and later say nitrate drop) started with the usual 1/2 - 1 1/2 " of sand. So it seems clear (IMO) that deepr than that is useful. I have no idea whether 6" is "better" than 4", etc.

The depth obviously also depends on the grain size.

[Mojoreef]

Wouldnt it just be easier to remove the food/waste/detritus before it begins to be reduced?????


Mike



http://www.thepsas.org/images/sig_logos/reef_frontiers_2_sig_logo.jpg (http://www.thepsas.org/forums/)

[Mojoreef]

Well, I disagree, and I think it is quite clear. Before DSB's became popular, many advanced aquarists had elevated nitrate. Most did, in fact, unless they resorted to denitrators or other schemes. When they added DSB's, the nitrate declined, ushering in the era of very low nitrate levels.
I dont know about that Randy. I dont think you could put that on the advent of sand in tanks. Thier were alot of things different back in those days, pumps, skimmers, testing equipement, education and so on. Maybe that the advent of sand gave hobbists more of an initial forgiveness of some husbandry mistakes.


Mike



http://www.thepsas.org/images/sig_logos/reef_frontiers_2_sig_logo.jpg (http://www.thepsas.org/forums/)

[brentp]

Originally posted by Mojoreef
Wouldnt it just be easier to remove the food/waste/detritus before it begins to be reduced?????

That is what I was thinking the whole time I've been following this thread.

[ldrhawke]

Originally posted by Mojoreef
Wouldnt it just be easier to remove the food/waste/detritus before it begins to be reduced?????


Mike



http://www.thepsas.org/images/sig_logos/reef_frontiers_2_sig_logo.jpg (http://www.thepsas.org/forums/)

Probably would be easier....lets see:confused:

With CPW you open a valve for less than a minute, manually or automatically waste a few pints to drain.....replacing the weekly water changes.......or...

You build a simple system to remove the solids. A good one I have seen uses 6 mixing eductors automatically sequenced to keep solids in suspension and the the flow goes to a double sock filter that should be cleaned out daily, Mangrove Tank to absorb waste, and in line carbon filter, a phosphate filter, through a multi compartment settling sump, and back into the tank. All controlled by an Octopus electronic controller.

Nah.......I'll stick with the complex CPW system.

Just kidding Mike...couldn't resist.:lol:

You have a great system. I only wish I had the space.:)

[Clay Glover]

Apologies if this question is redundant, this is a lengthy thread.

How long have you been implementing the CPW, and have you noticed any detectable increase in NO3 levels. Do you feed on the lighter side, or do you feed enough to keep fish overweight?

Good answers.... ;)

[Mojoreef]

LOL ldrhawke I guess when you tank is only the size of one of the sump compartments you think in different terms;) :D
I gues what I am trying to say is that your system may get rid of some of the long term build up waste, but I can see it dealing with P at all, plus it still has a blend of several different forms of nitrogen mixed through out it. I dont think you will be able to break bacterial bonds on the sand particles which is also binding most of the organics.
Your system although well thought out would likly make the anaerobic zone take hits on its every draining...no??? which would lead to an even less effective ammount of denitrification.
why not skip the decomposing phase??? thats what a dont understand.

Your discription of my system is pretty accurate but a tad out of context. the water flow is designed to recreate an enviroment for the critter i keep. Most reefs have a tad of flow;) the sump is really just a sump, the mangrove dont really do much either, but a gift all the same. on the controller, with alot of equipment you tend to need one.


MIke

[ldrhawke]

I guesS what I am trying to say is that your system may get rid of some of the long term build up waste, but I can see it dealing with P at all

YOU MAY WELL BE RIGHT, BUT SINCE THE PHOSPHATE DOES ACCUMULATE IN THE BED AND SINCE THE BED pH IS LOWER THAN THE WATER COLUMN. IT MAY AT LEAST HELP TO REDUCE THE AMOUNT OF PHOSPHATE IN THE WATER COLUMN. ONLY TIME WILL TELL. I DO BELIEVE SOME SORT OF PHOSPHATE FILTER WILL STILL BE NEEDED IF YOU HAVE A HEAVY BIOLOAD, BUT MAYBE SMALLER THAT IT WOULD OTHERWISE NEED TO BE SIZED FOR.

, plus it still has a blend of several different forms of nitrogen mixed through out it. I don't think you will be able to break bacterial bonds on the sand particles which is also binding most of the organics.

IT MAY NOT REMOVE WHAT IS BOUND, BUT IT WILL REDUCE THAT WHICH REMAINS OR GOES BACK INTO SOLUTION AND IS CONCENTRATING IN THE BED. AT LEAST IT IS NOT ALLOWED TO BUILD UP TO THE POINT OF CRITICAL MASS AND TOTAL DEATH.

Your system although well thought out would likely make the anaerobic zone take hits on its every draining...no???

THAT DEPENDS ON THE WASTING RATE TO SOME DEGREE. I CONTEND THE OXIC AND ANOXIC ZONES ARE NOT UNIFORM LAYERS, BUT HAVE PEAKS AND VALLEYS AND HIGH AND LOW VELOCITY ZONES. JUST LOOK AT THE VARIATION IN COLOR AND APPARENT ACTIVITY IN THE BED THAT IS EXPOSED ON THE BOTTOM OF THE TANK THAT YOU CAN SEE THROUGH THE GLASS (ACRYLIC)

I CONTEND THIS ASSURE YOU ALWAYS HAVE SOME DEGREE OF DENITRIFICATION TAKING PLACE. AND IT NOT YOU HAVE NITRIFICATION TAKING PLACE THAT REPLACED IT. WITH CPW YOU TRY TO MAINTAIN A FLOW INTO THE BED REMOVING THE NITRATES AND OTHER WASTE.


which would lead to an even less effective ammount of denitrification.

REMAINS TO BE SEEN. EVERYONE SEEMS TO BE CONCERNED THAT USING CPW WITH REDUCE DENITRIFICATION AND MOVE THE NITRIFICATION ZONE DEEPER INTO THE BED. EVEN IF IT DOES REDUCE THE DENITRICATION RATES, IT IS ALSO REMOVING AND STOPPING THE HYDROGEN SULPHIDE BUILD UP. IT IS ALSO INTEREFERRING WITH DENITRIFICATION. I CONSIDER THIS A MUCH GREATER POSITIVE.


why not skip the decomposing phase??? thats what a dont understand.

IF YOU WASTE ENOUGH A CPW TO A LARGE DEGREE YOU ARE DOING JUST THAT. THE HISTORY OF BB AND SHALLOW BEDS IS THAT THEY CAUSE NITRATE BUILD UP IN THE WATER COLUMN. OF COURSE YOU COULD ALWAYS INSTALL AN ELABORATE SYSTEM INTO TO COMPENSATE FOR THAT TO REMOVE THE SOLID WASTE LIKE YOU HAVE DONE.;)

CPW IS NOT MEANT TO BE A TOTAL SOLUTION. IT SHOULD BE CONSIDERED ONE MORE DEVICE AND TOOL TO GIVE YOU MORE CONTROL ON WHAT SHOULD NOT BE HAPPENING IN YOUR TANK.

[ldrhawke]

Originally posted by Clay Glover
Apologies if this question is redundant, this is a lengthy thread.

How long have you been implementing the CPW, and have you noticed any detectable increase in NO3 levels. Do you feed on the lighter side, or do you feed enough to keep fish overweight?

Good answers.... ;)

I installed the system when set it up in May. It has only been running with CPW for about three months.

I have seen some slight variation in NO3. It is always just barely detectable on the test. I contribute that to the heavy bioload and feeding.

My fish are fat and sassy. Although I have started watching how much and what I feed more closely now.

[ldrhawke]

TiTAN wrote on 01/30/2004 05:23 AM:
Hi,

Just wondering, I have been reading your thread on CPW and it sounds very interesting.

I am thinking this could be just like a Coil Denitrator in priciple as if the flow out the Coil-Denitrator is to slow it produces Hydrogen Sulphide(Could be wrong) with is exactly what you do not want so increase the flow. Well from what I understand that is exactly what you are doing with a CPW method? Removing Nitrates?

So from removing the water from the plenum at a certain rate you would still achieve the same result as in a coil Denitrator? Or not? Except you are not returning the water to the tank/sump?

I have been thinking about implementing your CPW method for a long time now and I think I will do it.

What would you change in your CPW setup to make it better or more efficient?

Thanks for your time.

Gunter
___________________________

There are some similarities. The idea is not to have hydrogen sulphide in either case. In the case of a coil you are producing it if you do not keep a high enough flow and it interferes with denitrification, but with CPW you want to remove what is produced in the bed.

You are right that if you only removed enough fluid with CPW that only hydrogen sulphide was eliminated regularly, you would keep the hydrogen sulphide from interfereing with the denitriifcation and have better denitrification in the bed.

If you only ran CPW to accomplish that and removed very small amounts of fluid daily, it would make for a better DSB system. That is another way to run CPW. Which anyone using it could opt to do.

Would I make any changes to make it more efficient? No. It gives a uniform controllable drain across the bottom of the bed and I can back flush it to maintain it if it should every start to blind. That's all I designed it to do.

This is a good question Gunter. Do you mind if I post it to the list?

______________________________


Hi,

It is not a problem at all, I was going to do it but I was not sure so you may do so whenever you like.

So now if you made the a system that used a CPW method and made the DSB +-5" instaed of +-4" and made a drip rate or flow rate high enough to make sure you did not get Hydrogen Sulphide you would infact have all the benifits of the DSB(Critters) its Denitrification Potential and have alot less of its bad side and plus you would not be wasting so much water as you would be feeding it back into the system as it would not have Hydrogen Sulphide in it.

I am wondering from your experience would that work and maybe even making the DSB +-6" so the flow could be set at a higher flow to get the nitrification and not have the Hydrogen Sulphid so it could be passed back into the system just like using a Coil Denitrator.

Thanks for your time

Gunter

____________________________

I considered doing that at the start and it is another option. I didn't because of four things 1)the coil would need to be very large to get adequate turn over and flow rates to be affective. (I don't have the space) 2) going though the expense and having another support system with a coil seemed to be a waste of money and effort. 3) I needed to make water changes anyway, it seemed foolish to go to all the effort to recycle a little water and then dump even more into the drain. 4) regular fresh salt mix elimates need for a lot of expense trace element additives


_______________________________

So if you added an extra inch of sand to you DSB and increased the flow of your CPW that would thoeretically elimiate the bad side of DSB period, becasue you can highten the screen in the middle and keep the top 2 inches turned over by the critters so this would be a good way to go don't you think?

Thanks again for your time

Gunter
-------------------------------------

Go for it.......:rollface:

[Mojoreef]

ldrhawke you dont really have to set up an elaborate system or some huge amount of flow to remove detritus. It just has to be properly designed. I have alot because my tank is sixteen feet long. the filters are just thier for a once and awhile running or when needed.
Anyway I am not trying to put your system down, as far as it looks it is probibly better then a standard fall off the log dsb. its just the whole concept of holding onto waste/food/detritus that does not make sence to me.

Mike

[ldrhawke]

Originally posted by Mojoreef
ldrhawke you dont really have to set up an elaborate system or some huge amount of flow to remove detritus. It just has to be properly designed. I have alot because my tank is sixteen feet long. the filters are just thier for a once and awhile running or when needed.
Anyway I am not trying to put your system down, as far as it looks it is probibly better then a standard fall off the log dsb. its just the whole concept of holding onto waste/food/detritus that does not make sence to me.

Mike

First, I never thought you were trying to put CPW down. Second, I don't think there is any significant difference in our approaches after looking at your web page. The only real difference I see is that you have a shallow bed and I have a DSB. In fact, I use the same Dolphin 3000 pump on my 60 g system that you use on your 1000 g system, and I also direct the flow around the tank using changing out lets.

The problem is even with my high energy input to capacity ratio, all of the fish poop is still not kept in suspension and most settles to the bottom. It quickly breaks up and my bed surface is always clean, but it does not get picked up and put into my bag filter. Unless you've potty trained you fish, I don't imagine your tank is much different.

Also, I believe a considerable amount of the fish and coral waste is liquid excretion.

Based upon the fact that all the waste is not easily physically removed, you only have two choices left...biological or chemical treatment. If biological treatment is done properly it is the cheapest and most stabile method.

With this in mind, I believe the more biological surface area you have in a tank, the better. Thus I am trying to improve upon the DSB and make it work better.

I believe the second most important item after biological treatment is the skimmer. Then chemical absorption with carbon and phosphate absorbing media to further improve the water quality.

A well designed biological system can take a lot of the load off of the skimmer and filters.

So you see, for the most part we are really in agreement:mixed:

[Mojoreef]

yep the thin layer of CC was an experiment that only lasted a few months, I found it was just trapping detritus like all substraight do. so I pulled in a few month back and went back to the original BB again. I find that I can get the vast majority of the detritus out, a quick blow of the rocks usually gets the balnce back in the water column.
Your system is very close to a sytem that charlie has been using for a number of years, te only different is that his is a plenum (or was your a plenum to??). But it does all the things your system is striving for. I think the big difference is however is the particle size. thier is done with larger particles following the jeaubert system a little closer.

good luck on it and I wish you the best of luck.

Mike

[DougSupreme]

are there any concerns with using CPVC as the piping in this system? Not sure if it saltwater safe, and I would rather be sure before I bury it in the sand :)

[ldrhawke]

Originally posted by DougSupreme
are there any concerns with using CPVC as the piping in this system? Not sure if it saltwater safe, and I would rather be sure before I bury it in the sand :)

CPVC is fine.....it can even take high temperature and stand up if you boil the water in your tank. :p

Infact, now that i think about it for a minute, it is a great idea. CPVC is better than PVC because you can get CPVC in a smaller size than the smallest 1/2"PVC comes in. This would allow you to build a plenum with more pipes for an even more even distribution of flow. i wish I would have used it.:rolleyes:

[salty joe]

Really interesting thread. It makes perfect sense to me to export pollution from where it is concentrated.

My problem is, I like the look of fine sand mixed with CC & rubble. I am thinking of lining the bottom with PVC drilled with 1/4 holes & maybe bigger farther from the siphon. Set eggcrate lined with 4 or 5 layers window screen. Any sand that sneaks past screen will get flushed out with waste water. It seems to me that this should create a fairly uniform "pull" on the bottom of the sand bed.

Even if channeling occured, I'm sure it will, I wonder how much nasty stuff would migrate from sand into plenum in a day from osmosis. Hopefully enough to make a difference.

The thing that has me bugged is a couple years ago, I set up a plenum according to Goeman. After 6 months, it solidified. It was replaced with a DSB accordind to Shimek, with no problems. Never ever used additives- always used a Ca reactor. I can't say for a fact the plenum caused solidification, but it is my gut feeling. And Goeman does mention using a butterknife or something to bust up hardened substrate.

[cuongvynguyen]

ldrhawke, thanks for the great writeup and answers. If I had seen this thread a year ago I would have set up CPW also as it looks to be a no risk, benefit situation which makes it a no brainer for me if I had to do it again.

Some members here were looking to have sand inhabitants in their tanks. My tank is far from looking as nice as any of the tanks here, but hopefully someone else will learn from my mistakes.

I have a 180Gal tank, of which my total volume of water is roughly 170 gallons. 250lbs of live rock, DSB, protein skimming, and occasional activated carbon and phosphate obsorber serves as filtration.

The tank has been setup with the DSB (0.5mm grain) for over a year and I have enjoyed keeping 4 queen conchs which are getting quite large (4+ inches and growing) as well as a pair of twin-spot gobies which do quite a job of stirring up the sand bed, and occasionally digging deep into them looking for meal. Other inhabits include 4 small clowns, 2 medium tangs, 1 watchman goby, as well as a red scooter blenny. My non fish inhabitants includes an assortment of soft mushrooms, 2 5' clams and a single acropora which can be seen here: http://reefcentral.com/gallery/showgallery.php?ppuser=19355&cat=500&thumb=1

Before the DSB the tank was setup with CC (which was a nitrate sink) for 3 years before tearing it down.

As seen in the photos I have lately been having to deal with high phosphates levels due to overfeeding. I try to keep some diatoms growing to keep the conchs happy and simply overdid it due to my own neglect and not maintaining the DSB at least bi-weekly if not weekly.

[ldrhawke]

Originally posted by salty joe
Really interesting thread. It makes perfect sense to me to export pollution from where it is concentrated.

My problem is, I like the look of fine sand mixed with CC & rubble. I am thinking of lining the bottom with PVC drilled with 1/4 holes & maybe bigger farther from the siphon. Set egg crate lined with 4 or 5 layers window screen. Any sand that sneaks past screen will get flushed out with waste water. It seems to me that this should create a fairly uniform "pull" on the bottom of the sand bed.

Even if channeling occurred, I'm sure it will, I wonder how much nasty stuff would migrate from sand into plenum in a day from osmosis. Hopefully enough to make a difference........

Joe,

The concept of a a plenum fewer small holes and being directly covered with filter cloth, reduces the normal short circuiting of flow through the substrate. The idea is to obtain a more uniform flow through the substrate and not have it all come through a shallow area with lower resistance and not move through an area that is partially built up with waste or more dense material. This will keep more of the substrate fed with the waste from the water column above.

As I have tried to explain, bigger holes and and egg crate covering them, allows for the fluid in the column to find the shortest and easiest path into the plenum. This will encourage short circuiting.

When you build a plenum your way, you will end up with a complete open space under the substrate, and the water column above will always find the path of least resistance to enter it. All of the flow into the plenum can then come from one small area.

A couple of you 1/4" holes could probably accommodate the total flow being discharged from the system.

Picture the flow in reverse to better understand what I am trying to do to get a more uniform draw through the substrate...........as a test hook a garden water hose, from your home, up to a 10 foot pipe drilled with a bunch of 1/4" holes. Each 1/4" hole can flow over a couple gpm each at only a couple of psig pressure.

Turn on the water.....you will see nearly all of the water flow will come out of the holes in the first couple of feet of pipe closest to the hose connection.

Take the same pipe and make the holes smaller, only 1/32 or 1/16" dia. Run the same test. You will now see water being discharged more uniformly form one end of the pipe to the other. Too many holes or too large of holes and you have the same maldistribution problem all over.

The same phenomenon is happening in a plenum in reverse.

[Shoestring Reefer]

Originally posted by ldrhawke
The concept of a a plenum fewer small holes and being directly covered with filter cloth, reduces the normal short circuiting of flow through the substrate. The idea is to obtain a more uniform flow through the substrate and not have it all come through a shallow area with lower resistance and not move through an area that is partially built up with waste or more dense material. This will keep more of the substrate fed with the waste from the water column above.
What happens when the filter cloth gets clogged? If the bed is not loaded uniformly with waste, some areas of the filter will be clogged sooner than others, and short circuting will occure.

Originally posted by ldrhawke

When you build a plenum your way, you will end up with a complete open space under the substrate, and the water column above will always find the path of least resistance to enter it. All of the flow into the plenum can then come from one small area.

Picture the flow in reverse to better understand what I am trying to do to get a more uniform draw through the substrate...........as a test hook a garden water hose, from your home, up to a 10 foot pipe drilled with a bunch of 1/4" holes. Each 1/4" hole can flow over a couple gpm each at only a couple of psig pressure.

Turn on the water.....you will see nearly all of the water flow will come out of the holes in the first couple of feet of pipe closest to the hose connection.

Take the same pipe and make the holes smaller, only 1/32 or 1/16" dia. Run the same test. You will now see water being discharged more uniformly form one end of the pipe to the other. Too many holes or too large of holes and you have the same maldistribution problem all over.

The same phenomenon is happening in a plenum in reverse.
I believe the maldistribution would only occure if the hydraulic resistance of the bed is low, ie, if the bed is shallow and a large substrait like crushed coral was used. With a deeper bed or a bed with finer material, what will realistically happen is this: water will flow uniformly through the bed, and only the flow in the plenum will be maldisributed. This is because the pipe maldistribution will be insignificant compared to the resistance of the bed.

First, picture it this way:
Drill TWO pipes with holes; one with 1/4" holes, and one with 1/32" holes. Place them side by side, and pipe water to them. True enough, the pipe with 1/4" holes will have undistrubited flow, and the pipe with 1/32" holes will have a more uniform flow out of each pipe. The problem with this analogy is that a plenum system or a buried pipe system is more than just the pipe or the plenum; the effects of the bed on flow distribution must also be considered.

Now Picture This
Drill a 1" pipe with 1/4" holes, and drill a 3" pipe with 1/32" holes. Place the small pipe with big holes inside the big pipe with little holes, such that water must flow through the 1/4" holes, then the 1/32" holes. Turn the water on, and the flow distribution out of the little holes will be no worse than the single pipe with little holes. Placing the pipe with big holes inside will not cause a flow maldistribution through the pipe with little holes.

How this relates to an actual set-up
In the pipe-in-pipe example above, the 1" pipe with 1/4" holes represents the piping in the plenum, and the 3" pipe with 1/32" holes represents the bed. Flow within the plenum may be non-uniform, but flow distribution through the sand bed will be affected by the sand bed, not the plenum piping.

[Flanders]

Did you take any precautions (screens, etc.) to make sure the jawfish don't short-circuit your plenum? Most of this discussion is over my head, but I wondered about the jawfish.

[ldrhawke]

Originally posted by Flanders
Did you take any precautions (screens, etc.) to make sure the jawfish don't short-circuit your plenum? Most of this discussion is over my head, but I wondered about the jawfish.

The whole purpose of thr plenum design I recommend is to eliminate that concern and problem. The Jawfish digging a hole is a good example.

Even if the Jawfish dig down and expose part of the plenum, you still get a draw down through the rest of the bed because the exposed area has a highly restricted flow from the exposed zone because of the small orifices. If you had large orifices in the plenum, all of the flow would be pulled throgh the Jawfish hole. Very similar principle we use in our industrial processing system for even air distribution into waste.

[Dr-BYTES]

what is the material your drainage cloth made of any possibility of it rotting after years in saltwater.I am setting up a cpw system on my new 65 gal and i want to make sure i get everything right

[ldrhawke]

Originally posted by Dr-BYTES
what is the material your drainage cloth made of any possibility of it rotting after years in saltwater.I am setting up a cpw system on my new 65 gal and I want to make sure I get everything right

You can buy polyester felt type material used as a soil drainage barrier at Home Depot in the garden dept. Any of the synthetic felts and screens will be ok for saltwater. Wrap the piping like you would a package with a couple of layers. Use coarse crushed coral if it is a DSB.

Make sure it is piped so that you can reverse the flow to backwash it. Two ball valves and a Tee should be all you need connected to the drain line. This will allow you to hook up an external pump and feed backwards into the CPW system. Reversing the flow for 10 or 15 seconds is all that would be required when you do back flush it.

The drainage flow rates are low and blinding should not be a problem. My system flow is still fine and has not needed to be backwashed since I installed it, but it may eventually. It is a good idea to plan ahead.

[Dr-BYTES]

thanks for the info one more question do i use crush corel for the whole bed or crushed corel on the bottom and sand on top
also the 1/32 holes would it benefit then being on the side of the pipe or on top

[ldrhawke]

Originally posted by Dr-BYTES
thanks for the info one more question do i use crush corel for the whole bed or crushed corel on the bottom and sand on top
also the 1/32 holes would it benefit then being on the side of the pipe or on top

Personally I would use all Carib Special grade crushed coral. That is not to say it will not work with a shallower sand bed. I just think the crushed coral will have less of a tendency to blind.

Point of Interest. Recently I have read a number of reports describing simultaneous nitrification/denitrification taking place in municipal wastewater treatment plants. In large racetrack carousel systems that use aerators to pump and aerate, forcing the water around the race track in an oval. Inbetween the aeration/pumping stations the oxygen is used up so rapidly, my the aerobic microbes, that denitrification takes place in the quiet zones. An aerobic waste treatment system will go anaerobic with 15 to 20 minutes, if oxygen is not continuously supplied.

When testing the CPW plenum I found the discharge was not only anoxic, but it would start producing H2S if it wasn't regularly wasted.

Drill the holes on the side of the pipe. I used additional lengths of pipe and set them in loose to partially fill the gap between the the CPW plenum piping. I did this to keep the felt cover from totally collapsing around the pipe from the weight of the sand.

[Dr-BYTES]

i have 1/2 in schedual pvc 40 pipe which is pretty thick stuff u think a 1/16 holes would be ok or must it be 1/32

[ldrhawke]

Originally posted by Dr-BYTES
i have 1/2 in schedual pvc 40 pipe which is pretty thick stuff u think a 1/16 holes would be ok or must it be 1/32

That is dependent upon the size of your tank and the rate of CPW. Figuring you will remove about plus or minus 1 gpm. A larger tank may want to drain at a higher rate.

If you drilled 1/16" holes, i would estimate that each hole would approx. drain about .05 gpm. Or 20 ( 1/16") holes would be needed in total to drain 1 gpm.

For 1/32" holes you would need 80 to 100 holes to drain 1 gpm.

This will give you some ball park numbers to design around.

[schanz]

Curse you IdrHawke.
Now I will always be looking at my DSB wishing I had pipes under it. Just one more thing to make my tank libido inferior.

Oh well, I wanted a different tank size anyway...

[Dr-BYTES]

the drain cloth from home depot i can get is used for gardens
laid under topsoil to prevent weeds from growing its colour is black one side of the cloth is sorta shiny and the other dull is this ok

[ldrhawke]

Originally posted by Dr-BYTES
the drain cloth from home depot i can get is used for gardens
laid under topsoil to prevent weeds from growing its colour is black one side of the cloth is sorta shiny and the other dull is this ok

If I remember correctly that material is more like a fine screen. They also have a gray felt like material, that would do a better job of keeping the fines from plugging the holes in the pipe. I bought a whole roll of it and have enough left over to do 100 tanks. If you want to pay postage let me know how big a piece you need and I'll mail it to you. Just drop me a private note with your address.

[Dr-BYTES]

ok the material i have is dark grey and is like felt. i am finnished designing and and drilling my grid do i have to glue each joint
the piping fits pretty snug in the joints just wondering if gluing each joint is required

[ldrhawke]

Originally posted by Dr-BYTES
ok the material i have is dark grey and is like felt. i am finnished designing and and drilling my grid do i have to glue each joint
the piping fits pretty snug in the joints just wondering if gluing each joint is required

Not required but a good idea. It isn't worth the trouble it may cause to have a joint come undone for any reason after it is installed and covered with substrate. How large is your tank?

[getwet]

Wow... .long thread.

Simply brilliant idea...I can't believe there is even a question on it...it's soo obvious once someone points it out. I actually thought about putting a drain in the bottom below the plenum so I could siphon off the stuff years ago, but spending a week tearing down the tank for it....well, I'm too darn lazy.

I don't think you're losing denitrification...a rapid pull of water into the bed once a day, I don't think would effect it that much...have to look up denitrification flow rates in the denitrifying filters. But chances are with a 4-6" bed, you are not replacing all of the water in the bed daily....that means it's still a low flow rate, although you may still be losing some of the effect.

Also, I wonder about using fine grain sand. In conjunction with standard DSB "critters" it might be fine. You're not going to really lose any flow rate, it's just a matter of creating channels and concretion of the areas that aren't channeled. Good churning via jaw fish, wrasses, worms, cukes, etc could minimize this????

Just a thought.

I SERIOUSLY doubt you will see any detrimental long term effects. It doesn't make sense on what is already known with DSB's, and UG's.

[Dr-BYTES]

My tank is 65 gal and may i say idrhawke you may very well have the solution to whats been troubling reefers all these years. Some times the simplest answers to complex questions turn out to be correct i wonder how many years went by when man pushed square wheels before some one came along and said hey lets cut the corners and a era was born. either way if your method works or not in the long term. At least u stepped up to the plate and took a shot and for that i thank u.

[H20ENG]

ldrhawke,
Just thinking out loud here, of backwashing the filter cloth.
I would think that you definitely wouldnt want to do this until you have been wasting from the plenum, bed, etc for awhile.
If you backwashed the drain system without wasting first, it could send a very toxic mix back into the water column. I agree that you may need to backwash the drain, but this should be pointed out. It'd be a tragic mistake if done improperly.
Thoughts?

[ldrhawke]

Originally posted by H20ENG
ldrhawke,
Just thinking out loud here, of backwashing the filter cloth.
I would think that you definitely wouldnt want to do this until you have been wasting from the plenum, bed, etc for awhile.
If you backwashed the drain system without wasting first, it could send a very toxic mix back into the water column. I agree that you may need to backwash the drain, but this should be pointed out. It'd be a tragic mistake if done improperly.
Thoughts?

Excellent point.....this is one of the reasons I recommended back washing for only 15 to 20 seconds in one of my posts.

I don't think you will have that highly toxic build up with regular CPW draining, but it would probably be smart to follow the short back wash burst with a water change by draining out of the CPW system to help pull what you might have disturbed back into the drain. I don't think you would need to back wash more than once a year.

There is still a lot of information to collect to optimize the CPW concept. I wouldn't be surprise to find people that simply didn't partial weekly manual water changes using the CPW system and draining through the bed, found that it avoided the potential of DSB over load.

[aquamanathome]

What a good concept. I'm very new to reef keeping and have been researching to find the best way to set up my tanks, switching from FO. How fast do bacteria recover or multiply? I read somewhere that the amount of bacteria in a sand bed could double very quickly, and reproduce to the space and food limitations. It seems to me that not only are you removing the bad stuff from the bed but also any die off would create more room for the bacteria to multiply.

If you could slide or rotate the drainpipes could you further reduce the channeling by having the holes in slightly different locations?

[Chicago]

here's a pic of the system that i was setting up a while back with the same concept. the 300 gallon ruber maid comes with a drain hole. the pvc in the pic is cut with numerous two inch slites and thus the water is taken from the full area more or less under the phlenum. see attached pic

i just got a error message saying pic is to big ..any ideas on a get around for this on the to big pic?

[rpgraff]

if you are using the upload feature, then you need to resize the file with photoshop or some other imaging editing software that lets you resize.

[darrellh]

Hi ldrhawke,

Can you give us un update on how the nitrate measurements in your water column are doing? Are you now feeding as much as you were before adding CPW to your tank?

Thanks,
D

[TiTAN]

Greetings all,

I going to build my CPW\DSB\Coil-Denitrator and install it within the next 2 weeks.

Just a question regarding the flow through with denitrification systems. How much is the flow?

And with the design I was thinking of having +-3-5 drain holes drilled at diffrent points in the plenum to extract the water from, the reason being is that it would take water from various places inthe plenum and would move the water more evenly down through the plenum and not have fresh water move through the DSB at only one point.

Does this sound like it will be worth it as I will be running a constant flow through 2 of the drain holes and a wasting for a couple of seconds from the other drain holes.

And input welcome.

Thanks

[Frank Mularo]

I seem to recall back in the late 80s/early 90s that some company (I don't recall the name) sold a modified UGF that had a space underneath the plates that slanted inward, allowing any solid material that made it through the gravel to be siphoned off through some kind of valve. While not exactly the same system that's being discussed here, it would be interesting and relatively easy to retrofit UGF plates to form a plenum with a valve to drain the water from underneath. Perhaps it would be an easier and/or cheaper way to achieve similar results.

[robwsup]

This seems like a very plausible concept. If I was planning to set up a new reef anytime soon, I would definitely employ this method. I have seen and smelled what happens to a old DSB when taking tanks down in the past. To pull that nastiness out on a daily basis seems like a wonderful idea. The small amount removed would probably have little to no effect on the nitrite and nitrate processing bacteria distributed about the sand bed.

[T Sandman]

Hi John, How long did you let your substrate cycle before you started your controlled wasting? Do you have a proposed formula for hole spacing for a given area? Do you stir or level out your substrate at any time to insure even flow? And lastly, Would you say that your skimmer has increased output, decreased output, or stayed about the same as before the cpw system was implemented?

Thank you for your time.

[ldrhawke]

Originally posted by darrellh
Hi ldrhawke,

Can you give us un update on how the nitrate measurements in your water column are doing? Are you now feeding as much as you were before adding CPW to your tank?

Thanks,
D

Nitrates are still zero, but phosphates are up to .1 since I went back onto heavier fish feeding. I am using phosphate reducing chemical RowaPhos and polyfilter to try to get them back down. I have too many fish for a 60g reef system so it may be a continuing problem and need chemicals or polyfilter media to keep phosphate down.

I use the polyfilter because I am concerned about the quality of the tap water, and copper content, even after going though RO/DI and carbon filters. Florida is has a ground potential problem and copper from the plumbing system is common.

[ldrhawke]

Originally posted by TiTAN
Greetings all,

I going to build my CPW\DSB\Coil-Denitrator and install it within the next 2 weeks.

Just a question regarding the flow through with denitrification systems. How much is the flow?

And with the design I was thinking of having +-3-5 drain holes drilled at diffrent points in the plenum to extract the water from, the reason being is that it would take water from various places inthe plenum and would move the water more evenly down through the plenum and not have fresh water move through the DSB at only one point.

Does this sound like it will be worth it as I will be running a constant flow through 2 of the drain holes and a wasting for a couple of seconds from the other drain holes.

And input welcome.

Thanks

I have commented on Coil-Denitrator before. If you figure how big it will have to be to get adequate throughput, you will see it doesn't make a lot of sense. Have a small one that just drips a drop a second will not have adequate capacity.

I have not found nitrates to be an issue with CPW. In fact it is probably improving the the nitrification process in the sand bed by feeding it and making it more effective.

I am not following you hole drilling concept. Just drill 1/32" holes about every 3" along the side of the pipe and it will work fine. You don't need to sequence or partition the CPW.

[ldrhawke]

Originally posted by Frank Mularo
it would be interesting and relatively easy to retrofit UGF plates to form a plenum with a valve to drain the water from underneath. Perhaps it would be an easier and/or cheaper way to achieve similar results.

A conventional UGF has far too much open space and it would be difficult to keep it from short circuiting. Building a plenum the way I recommended is cheap and easy.

[ldrhawke]

Originally posted by T Sandman
Hi John, How long did you let your substrate cycle before you started your controlled wasting? Do you have a proposed formula for hole spacing for a given area? Do you stir or level out your substrate at any time to insure even flow? And lastly, Would you say that your skimmer has increased output, decreased output, or stayed about the same as before the cpw system was implemented?

Thank you for your time.

Go through the normal nitrification cycle and then start wasting through the CPW system. The whole idea of the plenum design I recommend is to reduce the amount of shorting circuiting when you have different substrate levels and resistance to flow. If you build it as I recommend you address that potential problem.

Skimmer output......I really can say. My skimmer must be a female. It is not predictable, I never know when it will skim or not skim.:p

Also, I have modified my 3" by 24" PM skimmer. It was designed to make all it bubbles using only a venturi injector. I have modified my PM added a EuroReef SEDRA KSP3500 needle wheel impeller pump to recirculate in the PM and improve it's performance. It works much better now.

[ldrhawke]

I've been busy with business, sorry for the delayed responses. I have learned a lot over the last year and my preconceptions of what it takes to have a reef system have dramatically changed.

Let me state again, CPW is only a tool to improve upon and make you system more stable. The idea is to keep nitrates and phosphate at zero in a reef system......everyone system is unique and has different loading on the biological processing capacity of the tank.

The loading on the biological system will vary all the time. Fish and coral grow and increase the loading. Any method that helps to keep nitrates and phosphates at or near zero should be used, or at least be available to be use, when things get out of balance. How close to zero you need to be will depend upon what you are keeping in your tank.

We introduce the nitrates and phosphates when we feed the system. Over half of the nitrate and phosphates the fish eat go back into the water in solution and not as a solid. Even if you collect all the solids and remove them, you have solved less than half your problem. A skimmer removes a lot of what remains and a stable biological filter will hopefully handle the rest. If it doesn't you may need polyfilter and chemical treatment to polish the small balance if you are keeping more delicate coral.

Despite the often imposed myth, a DSB does not add phosphates. It is a biological filter that may start to store excess phosphates when it cannot biologically process them, which can become a problem, if it reaches it storage limit. If they start to be recycle back into the system they cause havoc. CPW helps to keep this from being a problem by removing the waste were phosphates concentrate and maybe are partially going back into solution. CPW helps to feed both the anoxic and oxic bacteria and makes the substrate a more effective biological filter.

It is difficult to use water changes alone to keep your tank from starting to slowly build phosphates or maintaining the chemistry. Read this well written article. http://www.reefs.org/library/article/t_brightbill_wc.html

As you can see by this article and the math, you need an effective biological treatment process taking place in the tank in conjunction with good maintenance. I believe a DSB using CPW adds to and improves on biological filtration process to help keep nitrates low and hold waste phosphates were they are concentrating.

There is no way even 10 to 20 % or more weekly water changes will keep a slow build up of waste from becoming a problem sooner or later if you don't have other methods to reduce them. I believe in a BB system, with the reduced biological filtration surface area, you will always have a nitrate problem and water changes alone will not solve the problem. Depending on the coral you keep that may not be a problem. BB tanks with a large quantity of live rock and low fish loads will have less of a nitrate problem, but it could still slowly build. You may think everything is fine and all of a sudden SPS or delicate coral start to die, and a death spiral can occur.

In short, there is no simple answer in keeping a reef system, other than knowing what to do maintain the water quality. And that will vary with every system and the best maintained system can have pollution creep up on it if you don't respond when it starts to occur.

[goby1]

It was mentioned earlier in the thread that as a possibly better alternative to the pipes/32nd inch holes/cloth idea, one could support some egg-crate or similar device, cover it with a filter cloth, and then fill in several inches of sand on top. The removal of fluid would come about by means of half in pvc sections, that were drilled at intervals along their lengths. It was stated that this was a "horrible" (or something like that) idea, because of "short-circuiting." Well I think it's a better idea. Skip the pvc sections at that. Just have one drain from, well, anywhere within the plenum. I don't believe that there will be significantly higher flow through the sand, while draining, in regions that are in close proximity to the drain opening. The resistance provided by the sand layer is much larger than that of the water from one side of the plenum to the other, especially if fine sand is used. Thus, while removing waste from the region, the pressure gradient across the thickness of the sand will be much larger than that from one side of the plenum to the other, through the water, which means that the gradient across the thickness of the sand will not vary from one side of the plenum to the other. This means that the flow throught he sand will be even across the bottom of the tank. With this in mind, I advocate the system as outlined by whoever it was, sans the pvc pipes. I also think that finer sand would serve the system better, due to the higher resistence and the much larger amount of surface area. A continuous drip from this system would work well, as to further minimize pressure drop from one side of the plenum to the other.

[darrellh]

Goby1,

Welcome to the ReefCentral forum.

I agree with everything you stated, but you're overlooking one additional problem that will occur over time. Initially the pressure gradient thru the sand bed will be uniform, but as different regions of the bed begin to clog, the flow thru these regions will have reduced flow. This sets up a vicious cycle where the regions with less flow begin to clog even more. You're correct in stating that the pressure gradient at the plenum/sand boundary will be uniform, its just that the pressure gradient thru the sand bed itself won't stay uniform.

The idea of placing small holes throughout the plenum/sand boundary (pvc pipes) is that even though the sand bed will still have regions that clog more than others, at least there won't be any large areas near the plenum surface that end up with little or no flow. This assumes of course that the little holes themselves don't clog.

As ldrhawke explained a couple of times, the problem with a continuous drip is that doesn't develop hardly any pressure differential anywhere which means the flow can short circuit to the path of least resistance. Using high pressure surges instead will force the flow to spread across all of the holes more evenly.

Darrell

[goby1]

Thanks for the kind welcome! I believe we are at the mercy of the clogging to some extent. However, the feed back will be negative as opposed to positive, I might guess. As regions in the SB begin to offer a higher resistance (not ence like in my post before), there will be less flow and hence less clogging particles that pass through (or try). I'm not so sure about this however. I am much more sure about the placement of the drain, in how it's location is insignificant. Even with pockets of "clogged" sand, the fact that the SB presents a much higher resistance than the plenum means that the vast majority of the pressure will be dropped across the SB, not through the water in the plenum. Consider an electrical analogy. Two copper cylinders, say an inch thick, lined up end to end, with an inch or so gap between. One cylinder represents the plenum, the other the main tank volume. In the gap are several resistors of varying values, which represent various pathways through the SB. It won't matter where you place the leads of a power supply on the copper cylinders if you are concerned about the current through the individual resistors. This is because most of the potential that the power supply is attempting to offer to the circuit, well, it's all dropped across the resistors. This analogy attempts to demonstrate that the drain location doesn't matter. In terms of clogging, one would have to consider a change in resistance as a function of potential. I would expect that the resistance offered by regions in the sand bed would increase somewhere along the lines of the square of the velocity, so in fact a large differential in pressure across the entire system would cause a dispropotionate amount of flow through the unclogged regions. A better understanding of our problem could be gleaned if we knew more about the nature of the clogging, especially the size of the regions they represent. It would also be of interest to know the diffusion constant for the various"waste" species an nitrates in the water-SB matrix. We could then tune the removal rate and sand bed depth to optimum values. I don't understand the aerobic/anaerobic biological stuff at all well enough to devise an appropriate model. Cheers, Goby1

[goby1]

Ah yes, so the velocity^2 argument attempts to demonstrate that a slow drip would result in a more even flow rate throughout the SB. G1

[ldrhawke]

Thank you Darrell, concisely stated.

G1,

I too often often compare the Laws of Fluid Dynamics and electricity when trying to convey my thoughts. But, the comparative analogy between Ohm's and Kirchoff's Law's between those of Newton, Navier, Stokes, Euler, and Bernoulli only go so far before they have a tendency to break down. Then if you throw on top of that the dynamics of the biology and chemistry of life in trying to maintain a reef tank it becomes a rather elusive moving target that is difficult to fit into a mathematical equation. :( ........ I continually stand in awe when I look at the Tanks of The Month on RC and I applaud and envy those that have succeeded.

For all intense purpose what you describe is an across the counter UGF that can be purchased at your nearest PETCO. Applying the dripping concept to a UGF has been tried by many in the past with no measurable success for the reasons I have tried to explain before. If you think you have discovered a way to make it work, it is easy enough to do. I suggest building one that way to satisfy your beliefs.:rolleyes: