The Oase ProfiClear Guard is a device that uses a safe low voltage conductive sensor attached to a 20-meter cable. The sensor detects changes in water level and sends a signal back to the controlling device when the conductors are touching the water. This signal closes the brass solenoid valve, preventing water from flowing through it to top up the pond. Conversely, when the sensor does not detect water, the valve remains open, allowing water to flow freely through it.
 
The system is powered by a 240v wall-mounted control box that steps the voltage output for the sensor down to 12v for added safety. The device also has a useful feature that closes the valve when the power is cut off, preventing a scenario where the valve is left in its open state without the ability to switch it off.
 
The ½" solenoid valve now also features a fine mesh filter on the inlet side to prevent grit from entering the valve and damaging the device's internals.