atural ion-exchange media designed to remove toxic ammonia as water passes over it Controlling ammonia levels reduces stress on fish Creates a healthy environment when setting up a new aquarium Maintains ideal conditions in aquariums with higher than average fish stock, for freshwater use only For fluval filter models: 106, 206, 306, 406, fx5, 105, 205, 305, 405, 104, 204, 304, 404 1600 G (56. 43 Oz)