Abstract: A variable speed motor controller senses the electrical load on the motor in turning a pump. An output of the controller may be used to trigger a vent valve or power to the motor may be cut if the load level indicates a restricted flow of fluid into the suction side of the pump, such as would be caused by drain occlusion in a swimming pool. A sensor in communication with the suction side of the pump ascertains a vacuum/pressure level present and may be used to verify that an intended operational state for the variable speed motor and the pump is actualized, otherwise anomaly processing is invoked. This pressure/vacuum monitoring may be conducted through speed changes of the motor/pump.