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View Full Version : DSB with Plenum w/flush


androal
03/20/2008, 08:59 AM
Does anyone know of some good threads/sources of info I can read up on methods used in configuring a DSB w/plenum that can be flushed?

I am curious to learn more about this idea - even if the conclusion is that this is NOT a good idea.

Google searches and forum thread searches produce info that is typically dated around 2003.

Does anyone know if this approach was ultimately disproven/abandoned?

I'm not finding many (any???!!!) who are still advocating a DSB w/plenum where the water below the sand bed can be flushed?

ryan_paskadi
03/20/2008, 09:14 AM
Well, I believe that the consensus is that a DSB with plenum is no different than a DSB without. DSB's work at removing nitrates and encouraging increased sediment fauna, but long term can slowly build up chemicals and ditritus that can cuase increased algea growth and old tank syndrome. I like the idea of flushing the water underneath the DSB, and can only assume this will extend the life of you DSB before it produces problems.

I like DSB becuase I like the critters that live in it. I think a bulkhead under the tank attached to a ball valve would provide a good method for flushing the plenum. If I had unlimited resources I would do a RDSB that can be removed and replaced from time to time.

Sorry I have no links just opinions

androal
03/20/2008, 12:43 PM
Here is an image of the system I am building.

Not sure if the use of the term "RDSB" is necessarily accurate for this system, but it sort of describes what I am building.

Essentially the concept I am going for is to keep the DSBs separated in several different places where they can be closed off from the main system and tinkered around with if needed.

Also, I wanted the main tank to be BB with a lot of circulation.

What I am trying to figure out is whether or not it is worth plumbing the base of the 29 gallon refugiums so i can potentially flush the DSBs, or perhaps the evidence is conclisive enough out there that an adequate supply of sand sifters does the job well enough that this is not required.

Any thoughts?

http://reefcentral.com/gallery/data/500/18243855galRDSB.JPG

Steve 926
03/20/2008, 10:14 PM
Here is the thread you are searching for
http://www.reefcentral.com/forums/showthread.php?s=&threadid=289910

It is a long read & funny at times, but very interesting !!
I have this CPW plenum in a 50 gal since 7/07. so far everything is doing great & the nitrate level is 2 ~5 ppm. depending how heavy I feed the corals. I believe that it has helped the NO3 level & I intend to use another one in the next set up. You can build one, or purchase something similar by Azoo products & add the rest yourself ( egg crate & screen )

At the very least, I like being able to drain off some of the waste to help the sand bed remain active & not become a large dump over time.
Read the thread & Good Luck

Steve

:smokin:

androal
03/20/2008, 11:56 PM
Thx steve!

I actually saw this one.

Its pretty dated (2003) and was hoping to hear feedback from people who have actually tried this, and whether or not it has worked or not.

Glad to hear yours has been running since July!

From what I have gleaned so far, a major source of DSB debate has been around the issue of people not maintaining them properly and a subsequent crash kills the tank.

The thing is, I'm not seeing much on effective techniques for preventing a crash.

The general stuff I am reading either says:

1) Getting the right amount and type of sand sifting creatures will move the sand around enough to disturb the bad stuff or eat the bad stuff.

2) Some (few...) are advocating modest and occassional vacuuming and gradual and perpetual replacement of sand to keep it going longer

3) This CPW concept, which seems to make sense to my newbie way of thinking, but I want to hear from people who have done it as to whether or not it really works!

How frequently, and how often do you drain water from yours?

How did you set it up - with egg crate and screen or with an undergravel filter?

Wouldl you do things differently if you were starting over?

Steve 926
03/21/2008, 10:23 AM
One thing about opinions " There Are Plenty Of Them "

The last few pages of the thread contain a member " Bigdaddy" who set one up over a year ago with good results. He has been helpful in answering my questions about using one.
I know that the thread is long but you can pick out some good info. in it

I let the plenum mature 4 ~ 5 months before draining anything.
Now about 1 qt. a month. My total water volume is only 50 gal incl. sump/refug. so thats about all I want to do for now. If the NO3 rises too high I'll try a little more & see, about other remedies ( less feeding, better maintence, etc.)

I think that cleaning the sand bed is ok if done to a small area at different times, but I have a diamond gobbie that beats me to it, so much for that opinion
Replacing the sand is also ok in small sections but were talking several years possibly before doing that. I guess it all depends on your Bio load & husbandry " another opinion"

Nassirus vibrex & certih snails (spelling ? ) are great for the sand
bed. I have more certih than I can count & give them away gladly to my friends. the nassirus are great bottom sifters, I have about 6 ~ 8 of them.

Here is a site to purchase the drain part, you can add the egg crate & screen yourself if you do not want to make one. I think this is the way I will go the next time
http://www.aquaticeco.com/subcategories/462/AZOO-Circulating-Pipes/azoo/0

Here is a pic of mine, I had to make it in 2 pieces to fit past the euro brace (Acrylic Tank )

http://i182.photobucket.com/albums/x152/Steve0926/PICT0138.jpg

It is made out of 1/2" pvc ( the fittings raise it 3/4 off the bottom) & the egg crate give it a total of over 1" off the bottom. No need to glue all of the pvc it's a tight fit, but that's up to you. crazy glue works great for gluing the screen to the PVC.

I used a #3 ~ #4 coarse aragonite gravel, some have used crushed coral also, for the first layer 1 1/2 " ~ 2 " (Petco was the best $ for all the gravel & sand ) placed a fiberglass screen between the layers & used Caribsea (2 ~ 6 mm) live sand for the rest ( about 2")
I did recess the front edge of the entire set up about 3/4" so you will not see the screen & pipes. I used a 3/4' section of irrigation pipe (black) for the lift tube to fit into my black background rear panel. heating the tube slightly will allow you to place it over the 1/2"pvc with a tight fit. The top has a 1/2" pvc T fitting that is capped on the top but not glued. this will allow you to remove the cap & fill the drain with some water, re cap the T, & gravity will do the rest. on the out side of the tank is a 1/2 length of pvc with a ball valve as the drain pipe I remove the cap & drain the line to prevent the tank from draining accidentally when I am through
"Murphy's Law "

Sorry for the LONG WIND, but I believe that this system has some merit to it.

The originator of the forum "Iderehawk" had a great idea. I believe he went wrong in trying to reintroduce the waste water back into the system via his sump.

Good Luck with it if you try it, at the very least you get to drain some of that nasty stuff in the sand bed keeping it cleaner

Steve


:smokin:

androal
03/21/2008, 10:57 AM
Wow this is great!

The approach is logical to me.

I am definitely going to try it!

Will post pics and let you know how it fares!

hottuna
03/21/2008, 12:49 PM
I know people will flip out when they read this ,but you can do just as well using an undergravel filter..
any ugf will produce little or no nitrates if you cover it with at least 4" of substrate and really slow down the water flow through the uplift tubes..
carib sea gave me this idea several years back ...and it works..
run the ugf at normal flow for the 1st 3 weeks while the tank cycles...then do either one of 2 things: cap the lift tubes and run as a plenum...or really slow the flow down to a crawl...and denitrification will take place-no need for wasting option either..

androal
03/21/2008, 02:45 PM
Interesting...

When I put together the design, I realized it really is just a DIY UGF setup.

Check out the pics.

It took me <1hr to put it together with about $10 worth of parts at HD.

I'm thinking of runing the uplift tube over the top and down to the entry to my sump. Then adding a ball valve so I can back off the flow rate to a crawl - as you suggest.

The one thing that gives me pause with this thought is the point made earlier that you are just taking the nasties out from under the DSB and re-circulating it.

Would it be better to just plumb it to a drain and occasionally drain out the stuff under the plennum to waste? Or does the idea of just getting the junk out from under the bed and re-circulating work just as well because the system takes care of the junk, once its back in the water column?

http://reefcentral.com/gallery/data/500/182438069.JPG

http://reefcentral.com/gallery/data/500/182438070.JPG

Steve 926
03/21/2008, 10:17 PM
Great Build androal !!

The problem with using a down flow UGF plate, is that over time the plate will clog from the sand fines eventually working their way down to the plate. perhaps enlarging the slots of the plate will avert this problem, but that seems like a lot of work.

Paul B, a member of RC, is using a reverse flow UGF plate with dolomite at a constant low flow rate. He has posted good results & has had it running for years. Pm him

returning the waste water to the sump for recycling, created problems for the originator of the forum "Iderehawk".
If you go through the pages you will see what he incurred in trying to do this. I would guess that if you had a large water volume, 250 ~ 300+ gal. you may get away with it at a slow rate,
but that would make me nervous during a power failure.:eek1:

So for now I'll just toss the waste water during a WC & move on.

I can only comment on what I have experienced since 7/07, when I started using one of these plenum's, so far so good. Several other members report the same. I have spent a lot of time researching plenum's both pro & con, but I find it interesting that many public aquariums use them.

I look forward to any comments / idea's that can / may improve on this idea

Steve

:smokin:

buffalo123
03/22/2008, 08:35 AM
don't tell the UGF is going to make a come back. I ran my first reef with one back in the early 80s. I ran it for a short while and then took out the lifter tubes. It worked well but made a major mistake by treating a fish with ick in the reef killing all the corals. But the fish lived

androal
03/22/2008, 05:11 PM
Heres some more pics of the build:

The fist two pictures show the finished DIY plenum in the tank. You can see how I covered it with nylon screening. I am hoping that by wrapping it a few times with nylon screening it would prevent most of the sand from getting through and clogging the slits I cut into the PVC for draining?

I was not planning on using any further screens/layers.

Side View:
http://reefcentral.com/gallery/data/500/182438002.JPG

Top View:
http://reefcentral.com/gallery/data/500/182438003.JPG

The next two pictures show the system running in a tap water test so you can see how the overflow siphons are working.

The freshwater test seems to be working great! I am getting nice steady flow through the siphons into the main tank, and the "funnel-entry" tubes which really slows down the water entering the siphons - slowing the suction in the fuge side tremendously, but keeping a strong forceful exit into the main tank (took a while to figure that one out!).

Side View:
http://reefcentral.com/gallery/data/500/182438007.JPG

Top View:
http://reefcentral.com/gallery/data/500/182438010.JPG

Steve 926
03/22/2008, 05:51 PM
Looks Great, hope to see it running with good results

If you are going to use a two layer sand, coarse / fine, I would recommend that you use a screen between the layers, otherwise the fine sand will work it's way down into the coarse layer, eventually mixing with it & slowing the flow to the plenum. The coarse layer is basically for good drainage to the plenun, where the top layer is where most of your bio load is. one layer of screen should be good enough between them

Steve

:smokin: