RDSB questions

[orcafood]

Has anyone ever setup a RDSB where the water flows through a plenum underneath the sand bed? I'm thinking it might increase the RDSB lifetime significantly.

[mcgyvr]

Jaubert

[orcafood]

Anyone know if it was effective?

Also from what I could find Jaubert was utilizing a basic plenum setup? An anoxic zone with sand on top right?

I'm thinking the problem with rdsb is that the water flows over the top, settling detritus into the sandbed and lowering its life span. If water was introduced into a plenum underneath and then taken out of the bottom of the other side, the sandbed wouldn't foul and diffusion still goes on. Maintain the height of water in the sand bed just like a skimmer output.

[ca1ore]

Originally Posted by mcgyvr

Jaubert

The guy from Les Mis? Pretty versatile chap .....

[Fredfish]

What is the purpose of your dsb, keeping critters that need a deeper sand bed or denitrification?

If it is purely denitrification, there is no need for a deep sand bed. All the activity you are looking for happens in the top few inches.

dsp, rdsb, jaubert, rugf, miracle mud ... they all work.

As to the rdsb, I suspect you would need significant flow to keep gravity from moving fines into the deeper part of the bed.

[orcafood]

The old 5 gallon bucket rdsb only utilized the first few inches for dentrification? I was not aware of that I always had awesome luck with dsb except that they foul. Thus im suggesting a rdsb where water flows under the sandbed instead of how they were classically run with water over the top. Water flowing under the sandbed would allow dentrification to occur through a much thicker rdsb as the normally anoxic area at the bottom of the bucket would now be aerobic, the top would also be aerobic but no water flow. The water level is kept exactly at the sand bed level with a standpipe. Is this how jauberts design functioned?

My design is attempting to stop the chances of small particulate fouling the sand bed. Overall I want to use it for denitrification. I was thinking a big enough one of these could do some serious denitrification, like a 40 breeder full on a 200 gallon tank.

[NanoReefWanabe]

You will not get the full benefit of a dsb if you flow water from the underside.. as there will never be an anoxic area... you will still have tones of nitrate removal though...i am building a rdsb for my new tank... it will be about 15g tank full of sand...i plan to have the water to run through mechanical filter though before it goes into the sand... actually it will be mechanically filtered before even getting to the pump after the skimmer...i actually don't care if the filter floss becomes a bit of a nitrate factory as a good portion of it will be going to the dsb anyway... at any rate the floss will be changed every couple days anyway...

[orcafood]

I bet a thick enough dsb with water running underneath would have an anoxic area near the middle. Say a 15 inch dsb, 1 inch off the bottom in a 40 gallon breeder?

Another idea, what if the top of the sand was sealed to gas exchange. Now there would be a huge anoxic area.

[NanoReefWanabe]

sealing the top could be tricky... if you have the anoxic area you will be competing the nitrate cycle and producing nitrogen gas... that gas will have to escape somehow... check valves might work to allow air out... otherwise gas pressure will overwhelm the water pressure and it will stagnate...

Lol sooner or later someone is going to tell you to use marine pure blocks... lol

[orcafood]

Sealing the top can't be that hard right? I mean put a plastic bag over it with a rubber band haha, I don't think it needs to be a total seal. Kind of similar to how an airlock works when brewing beer. I bet a beer brewing airlock would work but seems unnecessary.

I've been reading about marine pure as well as matrix, but I feel a dsb with oolitic aragonite would have many other benefits to the system, mostly due to its meta-stability (weak buffering) up to pH 8.2. Best tanks I have ever had included large quantities of the stuff.

All this said I planned to use a rdsb in tandem with a large quantity of matrix. I don't like how marine pure leaches aluminum.

They are probably making the blocks (monoliths) via the 2 step stober process, why would they not just do it with silicone instead? Must be much cheaper to use aluminum or something. Or maybe they are using silicone alkoxide but with aluminum traces? Curious if they added aluminum to the so-gel on purpose or not hmm.

Matrix being acid-etched pumice is the better alternative. Not to mention it is very easy to make..

[NanoReefWanabe]

Originally Posted by orcafood

The old 5 gallon bucket rdsb only utilized the first few inches for dentrification? I was not aware of that I always had awesome luck with dsb except that they foul..

I have never heard that before... it doesn't make sense that only a couple inches would do the trick...i would think there is still quite a bit of oxygen in the first couple inches of sand...i was planning on using about 10" deep rdsb with 2" of water flowing over...i am hoping to achieve full conversion...i am also thinking I will be putting small critters on the sand to clean anything that falls in there... stuff like bristle worms and spaghetti worms , amphipods.. no crabs or snails though

[Fredfish]

Originally Posted by NanoReefWanabe

I have never heard that before... it doesn't make sense that only a couple inches would do the trick...i would think there is still quite a bit of oxygen in the first couple inches of sand...i was planning on using about 10" deep rdsb with 2" of water flowing over...i am hoping to achieve full conversion...i am also thinking I will be putting small critters on the sand to clean anything that falls in there... stuff like bristle worms and spaghetti worms , amphipods.. no crabs or snails though

From memory, a sand bed can go anoxic after as little as the first 1/2". Can't remember if it was Toonan or someone else that did the tests.

[orcafood]

Many people are switching from rdsb to siporax or matrix because of the problem with sand beds fouling over time. DSB/RDSB do foul eventually with the conventional setup, no doubt that this happens.

The other nice part about siporax or matrix is that when you want to break down or move the tank, to keep your entire bacterial population alive all you need is a bucket to carry your matrix/siporax and an air stone. Just treat the matrix/siporax as if it were/is alive.

I think that the rdsb has additional benefits to a reef tank other than just denitrification which is really just a bonus. Kinds of benefits (trace element concentrations) we couldn't hope to measure without some serious chemistry instruments.

[NanoReefWanabe]

The way I see those products working it is like reverting back to bio balls...i honestly can't see them not clogging up as well... to be honest I would think they will clog easier as there is no way for any thing to get in them to clean them... to be honest I have bought 3 of the bio block cubes for my 5g tank... how ever they are in a media bag on the other side of a wall of filter floss...

[orcafood]

Matrix and siporax work well. I cant attest to marinpure blocks, never seen them in use. The matrix needs to flow around it like a canister filter to work its best. A local fish store in the area uses it on all their fish stock tanks and reef.

I only have 60 lbs of live rock in a 200 gallon haha, no sand. I need more surface area. Not doing a sand bed again I want to easily transfer the tank. Maybe a rdsb would help, I just setup 5 more gallons of matrix in cansters up from 2 gallons. 7 full gallons of matrix should help a bunch I hope, I want to be at 12 gallons eventually.

I’m worried I will be misaing out of the benefits of a fine sandbed but I don’t want a conventional rdsb as it is a great place for detritus to collect. I was thinking about bulding a radial flow filter soon maybe that would solve the rdsb (and whole sump) from collecting detritus. I was thinking: tank drain -> radial flow filter -> reciruculating skimmer -> matrix/rdsb/return pump

https://m.youtube.com/watch?v=Z5ydauzFEyg

[orcafood]

http://reefkeeping.com/joomla/index....k-of-the-month

Though he has a decent amount of live rock, Carlinhos’ tank is a good example of proper use of siporax, which is pretty similar to matrix but slightly slower flow requirement. He was using rdsb until he realized how dirty they get. Also notice he is using a settling tank, all be it an archaic labyrinth design. A radial flow filter would take up way less space though, and you can put a drain on the bottom. Changing a filter sock would be as easy and turning a drain knob.

[ca1ore]

I will say that I have not had problems with my RDSB fouling ..... though, to be honest, that's an imprecise term to describe a range of potential problems. I recently increased the size of my 4 yr old RDSB, and in the process of checking it there were no observable issues. I have always found the 'secret' to be to not allow excessive amounts of particulates/detritus to build up.

[Fredfish]

Originally Posted by ca1ore

I will say that I have not had problems with my RDSB fouling ..... though, to be honest, that's an imprecise term to describe a range of potential problems. I recently increased the size of my 4 yr old RDSB, and in the process of checking it there were no observable issues. I have always found the 'secret' to be to not allow excessive amounts of particulates/detritus to build up.

How do you keep particulates from building up if all the water enters the sand bed from below?

[ca1ore]

Sorry? I run a 'standard' RDSB; not under flow.

[NanoReefWanabe]

Originally Posted by ca1ore

Sorry? I run a 'standard' RDSB; not under flow.

My intentions are to run all my water through Skimmer and settle out area prior to going through filter floss then to my pump to get pumped over the top of my RDSB I am cutters how you keep your particulate free...i Maddy wish to use your ideas...i have 200# of sand cleaned and dried waiting for me to turn the tank on... (Well build the stand plumb fill I guess.. lol)

[Fredfish]

Originally Posted by ca1ore

Sorry? I run a 'standard' RDSB; not under flow.

Ha, I was thinking reverse not remote.

[ca1ore]

Originally Posted by NanoReefWanabe

My intentions are to run all my water through Skimmer and settle out area prior to going through filter floss then to my pump to get pumped over the top of my RDSB I am cutters how you keep your particulate free...i Maddy wish to use your ideas...i have 200# of sand cleaned and dried waiting for me to turn the tank on... (Well build the stand plumb fill I guess.. lol)

Not necessarily particulate free, rather particulate minimized I feed my RDSB off a dedicated manifold pump, with water passing through a large chaeto refugium first. Chaeto is an excellent mechanical filter.

[orcafood]

I always used to use chaeto, until I saw some amazing tanks not using any at all. You think a radial flow filter or settling tank could help perform mechanical filtration similar to your chaeto?

I even saw a 120 sps that went, 16 gallon settling cone -> recirculating skimmer -> return. The guy even had to decouple the settling tank from his skimmer because it was remving nutrients too aggresivley Same setup as carlinhos basically, no chato but tons of siporax right after the settling tank and skimmer.