The Kent Marine Phos Reactor is primarily intended to be used with phosphate-removal media such as Kent Power Phos and Phosphate Sponge, however it may be used with numerous filtration media to best suit the changing needs of the aquarium. Depending on the choice of media, the Phos Reactor may be used as a fluidized-bed filter, exposing the maximum amount of the medias surface area to aquarium water, hence increasing filtration efficiency.