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. Use up to a maximum of 750grams of PhosBan, or a media height of 8inches. Recommended flow rate between 20-40gph, too much flow can grind PhosBan. Comes with 1/2" hose connectors. Use with any granular media, including Hydrocarbon2 GAC. Recommended up to 600gallons (2270liters).