The PhosBan Reactor 550 is designed with the upflow principle to achieve the most efficient use of PhosBan® or other chemical filter media. By pushing water from the bottom upward through a dispersion plate, it forces an even distribution of water through the media, and prevents channeling. It can be mounted hanging on the back of the aquarium or below the aquarium. Hose barb connections are for 1/2 inch i.d. tubing. Includes 1/2 inch barbed ball valve for flow control, and hose clamps. Use with any pump having a capacity between 100 and 250 gph, but regulate the flow rate to the recommended 20 to 40 gallons per hour with the included ball valve.