The Fluval FX5 is a large capacity, multi-stage external canister filter system. It includes a self-priming instant-start system that eliminates the need for manual siphoning and the unique click-fit AquaStop Valves regulate water flow and rotate at 55 degree angles which allow for fast set-up and leak-proof maintenance. Features multi-directional twin output nozzles to create specific water flows. Plus, a purge valve allows for partial discharge of debris without needing to move the unit. Convenient, easy to change lift-out stack of media baskets. For freshwater and marine aquariums up to 400 gallons.