When the water level is high, the float opens an air inlet valve in the body of the control. The air inlet valve is connected through 48" long polyethylene tubing to a snifter valve on the pump and has no direct connection into the tank. The snifter valve admits air into the pump but prevents the water in the pump from escaping back through it. Air is drawn into the pump through the air inlet valve, connecting tubing and snifter valve and carried out with the water into the tank. This operation continues until the volume of air increases to the proper amount, at which time the float closes the air inlet valve, shutting off the supply of air to the pump. The optimum relationship between the volume of air and water in the tank is thus maintained.