The Seapora Power Filter PF10 is a hang-on-tank power filter designed to provide multi-stage (chemical, biological, and mechanical) filtration through the use of a reusable bio-sponge and disposable carbon/floss cartridge. This filter is powerful and quiet, with simple installation and maintenance and adjustable flow control. Seapora has created this filter for a wide variety of tank types and sizes, featuring four selectable filter sizes for you to choose from to accomodate the size of your tank. The PF10 requires the installation of one Small size Seapora Carbon Cartridge as well as a Seapora Bio-Sponge, with one of each included in the package. Replacement Seapora Bio-Sponges and Seapora Carbon Cartridge refills are sold separately.