Any DSB pro, pls help?

[wedgee]

Sorry to bother u guys again, but I just cant live with the 20-30 PPM of NO3 in my tank (even though the corals seem good; i remember someone telling me to wait for few months then see the results...) much longer!!!

I posted something abt having a mini-DSB (too late cause i only knew abt in-tank DSB AFTER i setup my tank with rocks) in my overflow some time back.

It was only several inches thick, but i just increased the depth to 11"x6"x6"

Is this effective? AT just said in another post that if large sand was used, it'd have to be more than 5" deep (Me using Crushed Coral, alas! - another mistake brought on by LFS)???

The problem is it has water flowing into its bottom thru a gap on its right-show in red arrow (i used some sand to block it up but dont think its enuff?)

This is the front view of the overflow compartment...the main water inlet hole is on top...

[wedgee]

This is the side view...

[nivlac]

Your setup allows water, and oxygen to flow from both the top and the bottom. This is not good as the principle behind the DSB is to create oxygen starved layers where anaerobic bacteria will utlise N03 as a source of oxygen. I suggest you seal the bottom with a glass pane or something.

[Tanzy]

2 water inlets? Why do you have one at the bottom too?

If it is as describe in the picture than it is not a DSB not denitrification. DSB are deep to allow a layer of anoxic water and sand to form. This layer has virtually no water motion.

[wedgee]

Hmm i understand yr points, and I've thot of using something to block up the bottom inlet too! The impt thing is:

1) If i DO block it up, will it really serve as a good enuff "DSB" for my 3 foot tank? Can it reduce my NO3? If u guys can confirm this, i'd very gladly block off that flow of water (can i use a CD cover for this? It's the most convenient object i can lay my hands on right now-will it leech?)

Also, i noted dat when i increased the sand height a few days back, the freshwater i had washed the sand in was CREEPING out from the bottom out to the top layer (u know, when u drip FW into SW u can see the 'fumes'?) It was in a slow, steaming sort of speed:

2) Is this the slow speed needed for a DSB?

3) Or does it really have to be zero flow of water?

SORRY if i ask too much? Me just very very curious

Also, sooooo much debate has been going on abt bio-balls;

4) Shld i ditch them? And the ceramic rings?

I am thinking of removing them and putting some weed-algae in that compartment instead, (the one on the left) to hopefully suck up NO3...

THANKS FOR HELPING!!! APPRECIATE IT

[Achilles Tang]

Firstly, let me clear up a misconception about bioballs.

They are used in place of live rock for nitrifying effects eg. converting ammonia to nitrites and to nitrates by allowing the right kind of bacteria (aerobic bacteria) to grow and these thrive on a moist environment with lots of oxygen.

They do their job so well that they are called nitrate factories.

In a FO tank or a heavily-stocked reef tank, they work wonderfully well to convert toxic ammonia and nitrites to the much less harmful nitrates.

Unfortunately, due to their physical makeup, function and location, they do not allow anerobic bacteria to breed on them to process the nitrates to harmless nitrogen.

But due to research that DSBs and ample LR could be better and more natural biological substitutes, many aquarists have considered bioballs as 'old school'.

There is no reason why a wet/dry filter with bioballs would not work hand in hand with a DSB to provide a total solution.

In fact, if you use liverock in a wet/dry filter situation, that is probably no different from using bioballs. Unless you are using a very dense and big piece of LR where the centre can house a very low oxygen environment for anerobic bacteria to breed.

That said... many aquarist are moving to more natural biological methods.

For your questions:

1. A 'small' but tall DSB is better than a poorly setup pseudo DSB. Yes, it is proven that DSBs reduce NO3 effectively. I don't think you should use a CD cover, perhaps something more inert like a glass pane would suffice.

2. Yes. The only flow of water should be over the top of the DSB.

3. No fast flow through the DSB and out thru the bottom, unless you are talking about a Plenum system.

[wedgee]

AT - So after all dats been done, i guess i shld get something to seal off the water flow from the bottom ya? I'm thinking of using those acrylic that LHS fanatics seperate their LHS with...

Btw, how long does it take for a DSB to be effective? How can i tell if it works after some time?

Oh yes, are those ceramic rings useful? They seem outta place in a marine tank, so can i lose them? Me thinking of putting some weed macro ontop of the sponge, so gotta lose the rings maybe...

THANX THANX THANX!!!

[Tanzy]

Wedgee,

Take those bioballs and ceramic rings out slowly in batches as your system is still reliant on them for biological filtration.

AT,

There is no water movement through a plenum system similar to a DSB.

[wedgee]

I've removed the bio-balls and some of the ceramic rings from the oveflow, and another added half inch to my sand bed...also bot some fern-like macroalgae. Hope all this helps...sigh

[Achilles Tang]

AT,

There is no water movement through a plenum system similar to a DSB.

Ah yes, I made a mistake on that... what I wanted to say was a plenum has water at the bottom, a DSB doesn't.

Must be very tired already coz it was so late!