The Hagen Aquaclear Power Filter - 20 provides mechanical, chemical and biological filtration through its multi-stage filtration system. The filter's filtration volume is up to 7 times larger than comparable filters on the market. Its unique design filters aquarium water through a natural and silent waterfall, with the added benefit of creating disturbances in surface tension (bubbles) that will help to oxygenate your tank and create a healthier environment for your aquatic inhabitants. The patented flow control feature allows for customized filter performance for your tank; a faster flow rate for regular, healthy fish, or a slower flow rate for quarantined fish and small fry. The media basket prevents water by-pass around the filter media, ensuring that the water spends as much time as possible in contact with the filter media, maximizing filtration efficiency and effectiveness.The installation and maintenance for the Hagen Aquaclear Power Filter is quick, easy and hassle free and the unit comes equipped with AquaClear Foam, Activated Carbon and BioMax, three distinct medias that help to trap organic waste and debris, improve water clarity and cultivate and preserve healthy bacteria. In addition, AquaClear delivers an entire line of media including Zeo-Carb and Ammonia Remover exclusively designed for the AquaClear Power Filter. The filter is ideal for use in aquariums between 5 - 20 US gallons (18 - 76 L) in size and has a flow rate of 100 GPH.