The API SuperClean Power FIlter helps keep your aquariums water clean and clear! This line of filters features a whisper quiet leak-free design. The filters include a five step filteration system. These filters are perfect for both freshwater and saltwater aquariums without any needed modifications. The advanced filter cartridge technology includes a Crystal Bio-Chem filtration media cartridge, and helps with mechanical, chemical and biological filtration. For takes 5-20 gallons, use the Power Filter 5-20. For tanks up to 30 gallons, we recommend the Power Filter 30. Tanks up to 50 gallons would require the Power Filter 50, and larger aquariums would require multiple filters.