Originally Posted by
natclanwy
http:///forum/post/2806977
I'm sorry to say your canister will do nothing for nitrates the only things that remove nitrates are water changes, anerobic bacteria, and macro algae none of which are present in a canister filter. In fact with your maintence practices I would say it is probably producing nitrates, maybe not since you are keeping the large particles from entering the canister, but your canister really isn't doing anything if you are only servicing it once a year since the phosphate and silicate media need to be changed periodically.
Anaerobic environment, an aquatic environment with little available oxygen
Now just because the water goes into the canister with normal amounts of available oxygen does not mean it stays available and prevents anaerobic conditions (Exp. anaerobic digester)
Nitrate, Silicate, and Phosphate in my set-up are not detectable this is because my bio-filter and animals use all of it up so the media does not need to be changed periodically only when a change makes a need for chemical filtration.
The longer my filter goes without a cleaning the more Anaerobic Ammonium Oxidation or Denitrification I get. Yet You would need a huge canister to rely on it alone or slow the flow down and make it a anaerobic digester, this is what I have tried say from the start most canisters are to small to remove much nitrates biologically.