Abstract: Between the vertical tube walls and the blades of the rotating impeller are four vanes attached to the tube walls. In the area radially about the impeller, the vanes are pitched in a direction opposite to the pitch of the impeller blades. The impeller is rotated in a direction such as to force the water downwardly. The top of the tube is below the normal surface of the water and the vanes are inclined from the top to the bottom of the tube. The impeller is rotated at a speed sufficient to produce a vortex from the top of the tube to approximately the top of the impeller.