Clean your fish tank using Penn-Plax Cascade 400 110 GPH Submersible Aquarium Filter for Fish Tanks Up to 20 gal. This water filter offers physical, chemical, and biological filtration. It's a fully submersible aquarium filter that quietly delivers 45 gal. per hour of crystal clear water for your fresh or marine aquarium from 1.5 to 10 gal. in size. An activated carbon cartridge removes harmful chemicals, toxins, odors, discoloration, and other contaminants for your aquarium. An internal sponge optimizes colonization of beneficial aerobic bacteria. A large capacity aquarium filter cup allows you to choose your own filter medium. The aquarium filter also has a pump head with adjustable and directional water flow. Cascade internal filters provide better filtration; physical, chemical and biological while also aerating. A water spray bar option allows you to distribute water evenly helping aerate your tank. This fish tank filter can be placed horizontally and is easily hidden.