Anaerobic bacteria
really doesn't prefer nitrAte. It prefers oxygen. In most tanks, since low oxygen levels will kill fish, anaerobic bacteria doesn't do much to nitrAtes. What happens is when dissolved oxygen is low, the anaerobic bacteria can get oxygen ions from the nitrAte molecule, so it breaks the nitrAte down to nitrogen gas and oxygen.
In order to use it in an aquarium, you have to set up some means of creating a spot where aquarium water can go and lose oxygen. In order to do this, a "sump" has to operate at an
extremely low flow, at about 1 drop per second. It also can't have any dead spots, or the bacteria will turn septic and give off dangerous gases like hydrogen sulfide.
There are companies who makes "nitrAte filters" that work within the above parameters. The most widely sold ones are by
Aqua Medic.
I have yet to try one. I understand these units need to "cycle" seperately from the rest of the tank, and just like the main tank it takes 4-6 weeks.
As for "nitrAte absorbers," again they
really don't absorb nitrAte directly. Rather, they absorb dissolved organics that would otherwise end up breaking down to nitrAte. The bacteria in the tank that is processing nitrIte will still produce nitrAte.
