14 inch DSB in overflow? Help me make this work!

[runningrandy04]

Hey everyone,

So I've been trying to maximize every inch of my sump and have come to a realization that the overflow area is greatly wasted. My idea came from the "DSB in a bucket." Could I use the lower 14 inches of the overflow in my 75 gal reef ready as a DSB. I have a Mag9.5 / Mag 12 running between 600-900 gal/hr through the overflow depending on which return pump I am using.

My plan is to have both standpipes firmly set into the bulkheads. Place 14 inchs of sand in the overflow. The full syphon standpipe will be 17 inches high with a drain guard on it. My secondary drain is set to start flowing at 18 inches. My overflow wall is at 18.5 inches high. I will also be putting a piece of black acrylic over the overflow to block light.

I would love any input. If it fails, I can always extend the drain pipe to a bucket and pull the standpipe.

Concerns!
1. I will have to experiment with the depth of the sand to allow enough flow to keep detritus from settling but not stir up the sand. Should I start lower than 14 inches?
2. The "DSB in a bucket" recommends mechanical filtration before the bucket. Do you think finding the right flow will make mechanical filtration unnecessary?
3. Which sand should I use? I want to use dry Aragonite but what size? I want heavier grain size to allow greater flow but not big enough to suck in detritus.
4. I am currently cycling my tank. Should I start it now or wait until the tank is established so I can get a reading of how effective it is, if any?

[thegrun]

Anything more than 6" of sand will simply collect detritus, the denitrifing bacteria live in a narrow band of sand between the anaerobic and aerobic zones. There likely isn't going to be enough sand to help much but I don't see it causing any problems other than if you need to remove the standpipe for cleaning the sand will make that difficult.

[runningrandy04]

Originally Posted by thegrun

Anything more than 6" of sand will simply collect detritus, the denitrifing bacteria live in a narrow band of sand between the anaerobic and aerobic zones. There likely isn't going to be enough sand to help much but I don't see it causing any problems other than if you need to remove the standpipe for cleaning the sand will make that difficult.

Thanks for the reply,

To my understanding: the aerobic zone acts like the rest of the bio filter; that slim area between zones will break down from ammonia to nitrogen gas; and the anaerobic area only feeds off nitrate. I'm actually trying to minimize the aerobic section and increase the anaerobic section so it only processes nitrate and doesn't harm the nitrogen cycle when removed.

Due to the lack of responses, I may postpone this project until my tank is established. Make a proper experiment out of this.

[cloak]

Before you add a bunch of sand to your overflow you might want to see if you can achieve the results you desire without it first. Don't forget, denitrification can happen deep within your rocks as well. GL.

http://www.reefkeeping.com/issues/20...ture/index.php

[runningrandy04]

Originally Posted by cloak

Before you add a bunch of sand to your overflow you might want to see if you can achieve the results you desire without it first. Don't forget, denitrification can happen deep within your rocks as well. GL.

http://www.reefkeeping.com/issues/20...ture/index.php

Thanks for the reply,

This is essentially an old system being restarted. That system was up for 5 years I have had it down for 2 years but I previously had a Nitrate level of 10-15 ppm. Since then I have done an acid wash on the rock. I'm hoping that might increase rock denitrification. If it doesn't turn out to be enough, I'll initiate my experiment.

You know how it is, cycling causes all sorts of crazy ideas.