Abstract: A filter for an aquarium tank and apparatus for cleaning and aerating water within the tank. A pair of spaced apart but perforated walls are located above and spaced from the bottom wall of the tank forming an enclosure. Filter material is located between the perforated walls. A cylindrical housing extends through the perforated walls having a closed but perforated top end and an open bottom end opening into the enclosure. An upstanding tube extends through the housing having an open top end. Pressurized air is directed into the upstanding tube. A tube extends into the upstanding tube allowing water within the tank to flow into the upstanding tube. The air and water then flow upwardly through the tube and through the housing with the air escaping from the housing. The water then flows downwardly between the housing and tube and eventually upward through the filter material. Means are provided for reversing the water flow for cleaning of the filter.