PlanetCatfish.com

What do you think?
http://saltaquarium.about.com/od/protei ... denitr.htm

I think quite a few differneces exist between salt and sweet water.

The most important ones being that in salt water plants grow less, the salt is very expensive and saes are mostly much cleaner thans rivers and lakes.

The result is, that the animals expect much cleaner water, which is much harder, and more expensive, to provide.

I think we better stick to changing water, and those of us who life in water scarce places (which are most ofte nvery sunny) could try biogenic nitrate remouval throught plants in an outdoor pond.

When I built my DIY wet/dry I supported the grid that holds the eggcrate platform that the twin trickle towers sit on with four perforated two liters plastic nut jars filled with a mix of gravel and sand which in turn, sit in the sump. This was my attempt to provide slightly anaerobic zones for the purpose of dinitrification as well as for ballast.

Whether these actually work to any degree is unknown. The jars had to be weighted anyway and it was my hope they could double as a zone of denitrifying bacteria.
Anaerobic is really an inaccurate term as absence of all O2 is not desiralble. Anoxic is probably the more correct term and is what is desireable as a parameter of de-nitritors. I also change at least 75% of the total system volume of the water twice a week so either way nitrate concentrations are controlled.

Anoxic denitrification is possible in closed freshwater systems. Whether my design is doing it to any meaningful degree is very much up in the air(no pun intended). In theory they have a diffused flow through them perhaps slow enough to promote denitrification but in fact what I can say is because they are filled with sand and gravel they stay where I put them. There have been no negatives associated with this design whether it works or not as a denitrifier.