Help your finned friends breathe easily with Lee's Aquarium & Pets Under Gravel Aquarium Filter! This filter is designed to clean through a biological filtering process that supports the growth of beneficial bacteria， which promotes natural detoxification and maintains proper ammonia balance by circulating water flow through the gravel bed. It features a strong multi-level UGF plate with molded gravel guards to prevent gravel from entering the uplift tube. It also includes two premium carbon cartridges， coarse Discard-a-Stones， a fish-saver elbow， and a telescoping ring to easily adjust the height of the uplift tube.