The Aqua Light easy Refill system provides a very reliable way to monitor and replenish the evaporated water in the aquarium. The unique optical sensor switches the water pump with high precision and keeps the water level at an optimal level. The sensor is a mini optical infrared sensor for extremely precise water level regulation. It requently checks/refills the water level with a maximum tolerance of 5 mm. This means lesser water fluctuation. The controller of the Aqua Light easy Refill system has a magnetic mount which enables safe installation in tanks. The built-in alarm provides additional security in your aquarium. The easy Refill system works with 12V security voltage.Aqua Light easy Refill+ water refill system for aquariums+ automatically refills evaporated water+ always the same water level at the aqaurium+ with optical sensor+ magnetic mounting of the sensor+ no cables in the aqaurium+ complete system with pump, sensor, tubing and accessories+ for fresh and marine water suit