A trouble-free biological filter designed with adjustable 1" dia. uplift tubes for better water circulation and multiple-plate construction. Includes airline tubing and Discard-A-Stone and features the fish-saver elbow. Advanced design allows a separate plate installation and also has optional flow-thru set-up for use with a power head. Made of special quality plastic which resists splitting and cracking. Available in three different styles to fit rectangular, hexagonal, octagonal, and flatback aquariums.