Filter and water recirculation system

Claim 1

For an aquarium with water, an undergravel aquarium filter and water recirculation system having a base member adapted to rest below said gravel, a rigid outer water-carrying tube carrying water from the bottom of the aquarium and discharging the water on top of the water within the aquarium, a rigid inner air-carrying tube located within said outer water-carrying tube to discharge air into the path of flow of the water being carried by said water-carrying tube, said water-carrying tube having a substantially vertical portion and a substantially horizontal portion connected together to carry said water vertically upward and discharge said water respectively, said substantially horizontal portion including an aperture located substantially directly above said vertical portion, said inner air-carrying member being passed through said aperture to descend within the vertical portion, and means for permanently fixedly securing said inner member at a selected height with respect to said watercarrying member, said inner tube being substantially coaxial with the vertical portion of said water-carrying member, said horizontal portion being located above the water level within said aquarium, said height being set by pushing and pulling said rigid inner tube downwardly or upwardly, respectively, with respect to said outer tube by manipulating said inner tube from the portion of said inner tube projecting above the aperture in said outer tube.