Nitrates are the [almost] last step in the N2 cycle. Ammonia is oxidized into nitrites and nitrites are oxidized into nitrates. Unfortunately the only bacteria that can convert nitrates into nitrogen gas are specialized anaerobic bacteria that are very difficult to culture in the aquarium. This 'forces' us to do partial weekly water changes to remove nitrates along with other impurities.Been testing almost daily to see where my numbers are and everything checks out fine except nitrate. It is elevated just to the next color level on my API test chart. I've purchased the PRIME stuff that detoxifies the nitrate but it still is reading the same. Does it take a while for the reading to level off? Anything else to do for high Nitrate readings?
Ammonia is the result of fish respiration and decaying organic matter. If we reduce the ammonia that ultimately becomes nitrates, we're ahead of the game.
Living plants assimilate ammonia and to some degree nitrates so having lots of plants, even floating, helps purify the water.
Being careful to not over stock, not over feed and keeping the tank and filter clean to reduce the decaying organic matter also reduces nitrates that get produced.
Finally there are products that can help us reduce tank generated Nitrates. For instance, Seachem Purigen is a synthetic polymer resin that adsorbs dissolved organic compounds (DOCs) before they decompose further to produce nitrates.
There are also products like Fluval Labe Series Nitrate Remover and API Nitra-Zorb that are synthetic 'scavenger' resins that will adsorb nitrates.
HOWEVER, for most, just doing weekly partial water changes is all you need to keep nitrates low and stimulate the tank with fresh water (just as rain does in the amazon).
Also, Prime merely detoxifies ammonia, nitrite and nitrate for ONLY 24-48 hours giving beneficial bacteria time to process (removing chlorine CREATES AMMONIA). It does not remove anything.