Fluval Nitrite Remover for 07 series are designed specifically for the Fluval 07 external canister filter series, Nitrite Resin infused Pads perform double duty as both an effective mechanical and chemical media. Nitrite is often a problem during the setup phase of an aquarium. With the Fluval filter pads you can react immediately and remove the toxic nitrite from the aquarium water.Fluval Nitrite Remover for 07 series+ specifially desgined for the 07 sereis external filters+ for 107/207/307/407+ effective at removing and reducing nitrite+ effectively traps floating particles for clear water (debris, excess food, and waste)+ helps prevent fish loss+ supports beneficial bacteria for a healthier aquatic environment+ custom fit to increase filtration efficiency+ for best results, replace monthly or as required after testing water+ convenient 3-pack/6-pack format+ for use in freshwater and saltwater aquariums