The Fluval Nitrate remover cartridge is for use with the innovative Fluval External filters G Series and will remove increased nitrate concentrations in fresh water aqauriums. Nitrate concentrations should not exceed 20 mg/l in frehswater aquariums. Planted aquariums require approx. 5 mg/l of nitrate as a source of nitrogen for healthy plant growth. In a 300 or 600 l freshwater aquarium with 30 mg/l nitrate concentration, the use of the Fluval Nitrate remover cartridge will quickly remove all excess of nitrate in a couple of days. If left in the filter it will then maintain a low nitrate level for a period of time that is strictly dependent on the type of aquarium (quantity and type of fish, type of fish fodd and so on). Nitrate irreversibly trapped and bound and will not leach back into the aquarium water. The continuous use of the Fluval Nitrate remover insert in aqauriums with persistent nitrate problems is an effective solution against nitrate accumulation. If used as a quick solut