Efficient up-to-date design treats organic wastes naturally, ensuring crystal clear water in freshwater or marine aquariums. Twin lift tubes and a unique wavy plate design resist clogging and evenly draw water through the gravel bed-ensuring that the entire bed is available for bacterial breakdown of toxins. Gravelguards at the base of each lift tube and high collars prevent gravel and fish from getting beneath the plate. Also features long-lasting air diffusers for high volume flow of bubbles and strong circulation.Includes two carbon cartridges for immediate setup. Requires an air pump for operation. Replacement cartridges are available. We recommend monthly cartridge changes.