Marina Canister Filter Replacement Zeolite Ammonia RemoverMarina Ammonia Remover is a natural ion exchange media that removes toxic ammonia as water passes over it. Use it to provide an healthy environment when setting up a new aquarium or maintaining one that contains higher than average fish stock. Eliminates Toxic Ammonia Reduces Stress on Fish Ideal for New or heavily Populated Aquariums For Freshwater Use Only For CF20, CF40, CF60, CF80