When your overhead tank is empty Aquajack water level controller automatically switches on the Pump. When the tank is full it switches off the pump. Aquajack water level controller also switches off the pump when the underground sump is empty and switches on when it is full . Aquajack water level controller comes in a wide range to suit all brands and types of pumps like mini monobloc pumps, centrifugal pumps, compressor pumps, jet pumps, submersible pumps etc., of any horsepower; single or three phase. The range includes Aquajack Mini Solo & Twin, Aquajack Essentia Solo & Twin, Aquajack Basic Solo & Twin, Aquajack Classic Solo & Twin, Aquajack Tristar Solo & Twin, Aquajack Tristar Sumo Solo & Twin and Aquajack Submarine.