When the liquid level falls below the probe, a fixed time delay begins and the LED flashes Red. This time delay prevents rapid cycling of the output relay and its load. At the end of the time delay, the output relay energizes and the LED is Red ON. The pump is ON to fill the tank. The relay remains energized until the liquid level rises and touches the probe. The output relay de-energizes, turning off the pump, and remains de-energized and the LED is Green ON until the liquid level falls below the probe. If the container is non-conductive or insulated, an additional probe must be installed as the COM connection where it will always be submerged.