This 7 tall reactor is designed for use with tanks up to 50 gallons. By pushing water from the bottom upward through a dispersion plate, it forces an even distribution of water through the media. Because of its small size, the Little Reactor is ideal for use with Nano and Pico aquariums, and it fits perfectly in standard frag display tanks used at frag swaps Little Reactor - Two Little Fishies Includes 1/2 inch barbed ball valve for flow control, and hose clamps. Because of its small size, the Little Reactor is ideal for use with Nano and Pico aquariums, and it fits perfectly in standard frag display tanks used at frag swaps. If you're using the NPX Bioplastics we recommend you also purchase the Phosban Reactor NPX Screen. By pushing water from the bottom upward through a dispersion plate, it forces an even distribution of water through the media, and prevents channeling. Small Water Pump Two Little Fishies PhosBan Reactor 150 Replacement Sponges - Neptunes Pompe A Eau Two Little Fishies Little Reactor is the latest and smallest Two Little Fishies reactor. Two Little Fishies Little REBORN Calcium Reactor Media 4Kg (8.8lbs... The Little Reactor 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.