The Superfish Aqua Flow 50 Internal Aquarium Filter is ideal for small tropical or coldwater fish tanks up to 50 litres in size. The easy click system makes maintaining and changes filter sponges really easy.There is a dual action filter medium with activated carbon as standard or the option of crystal clear cartridges if required. Simple to fit and simple to maintain these filters have adjustable outflow, spray bar, suckers for attaching to the side of the aquarium and filter cartridge in the set.