I agree that live rock can aid in denitrification. That's why you want to have some bigger rocks instead of a ton of smaller ones. With the larger rocks deep in the center there will be a larger anoxic zone so denitrification can take place.

But as far as proving wether a sand bed can aid in denitrification, couldn't someone with access to the cheap Southdown sand do a simple test?

All you probably need is a 10 gallon tank, a powerhead, and a dead shrimp, and a little live sand. You don't even need lighting (just something to control evaporation).

Put a four inch sandbed in the tank and cycle it like you would cycle dead sand normally stirring the sand regularly. After a while the Nitrates should spike, and now if the sandbed is left alone the theory can be tested.

Maybe the same could be done with the Coraline algae idea. Culture the algae on a smooth serface like a sterilized beer bottle or some small tupper wear until it encrusts it completely. Then put it in a small bare tank with detectable nitrates and see if it does anything. You won't need a light in the tank to keep the algae alive just keep it by indirect sunlight. I've seen plenty of Coraline grow in a sump under a tank in front of a window. The only thing that might affect the experiment is if green algae begins to grow.

Any other ideas on that, or has someone already done an experiment similar to this?

Marcel,

As far as proving a sand beds nitrate processing ability, well I guess this has been proved by numerous hobbyists, etc

Take a “Classic Berlin with a nitrate problem, (” bare bottomed”) add a sand bed, wait a few months, and the nitrate problem goes away.

Deep sand beds, are really not a new idea. They have been set up by biologists like Dr. Ron and Rob Toonen for years. But like many things, they are just now becoming mainstream “vogue” (Protein skimmers were being used by the Germans in the 1970’s)

Regards,

Scott

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The definition of an expert is a washed-up drip under pressure.
You can see my reeftank at http://www.homestead.com/spasse/

Live rock does in fact help to get rid of nitrates, in essentially the same way that live sand does. The rock is porous, and diffusion to the interior of the rock, like diffusion to the depths of a 4"+ sandbed, is quite slow, but finite. It is this very slow exchange that lets denitrification happen, because it can only happen under conditions in which there is very little to no oxygen present. The anerobic bacteria responsible for reducing nitrates live in this sort of environment. If you cut open live rock you will be able to see (and smell) the anoxic zones, they will be stained black from the hydrogen sulfide and probably smell a little bit too.

It turns out that live sand is better at denitrification than live rock, because it is more porous. But you can have complete denitrification with enough live rock and a small enough bioload.