Abstract: A pump has a large upper chamber containing an outlet, a smaller lower chamber containing an inlet, a flared transition portion between the lower and upper chambers, a driven vertical impeller extending within the chambers and the transition portion, and an aeration device in the transition portion, the aeration device being a projection into the transition portion with an upward slope facing the movement of the impeller therepast and an edge in the direction of rotation of the impeller, and an air valve controlling air flow through a channel leading into the pump at the edge of the projection.

Abstract: An aquarium filter tank pump has a housing with a large upper portion and a small lower portion joined by a transition. A motor driven impeller generally conforming to the inside of the housing draws water into an inlet in the bottom of the lower portion of the housing and discharges it through a generally tangential outlet tube extending from the upper portion and containing an adjustable flow constriction control. A bypass tube extends downward from an opening in the transition so that restriction of flow through the discharge tube controlling pump output is balanced by flow through the bypass tube.

Abstract: A check valve for use in a tube has a closure element hinged in the tube which nests within one side of the tube in the open position and pivots to substantially block the tube in the closed position. The closure element has a bottom edge and an upward extending edge which intersect at 90 degrees at the diameter of the closure element, the edges meeting the side of the closure element at points disposed one above the other a distance apart greater than the diameter of the tube. A tubular seat with upper surfaces conforming to the edges of the closure element in the closed position may be inserted below it as a press fit in the tube and the closure element may be hinged to the seat.