Two Little Fishiest Hoban Reactor;The Hoban Reactor Is Designed With The Up flow Principle To Achieve The Most Efficient Use Of Hoban 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;Two Little Fishies Phosban Reactor;The PhosBan Reactor is designed with the upflow principle to achieve the most efficient use of PhosBan or other chemical filter media