Nitrates will be lowered to almost undetectable levels. The time frame depends on several conditions. Nitrate is the result of pollutants in the aquarium. An aquarium with relatively low pollution can be treated in as little as 5 days. A heavily polluted tank can require several weeks to treat. In either case it is extremely helpful to limit the amount of waste entering the tank. The main cause of excessive waste is overfeeding. We therefore strongly recommend feeding as little as once every other day while recovering a failing tank with Algone.