SpectraPure Multiple Tank Liquid Replenishers are the most advanced means of controlling liquid levels on single or multiple reservoirs and are ideal for replenishing evaporated water in aquariums or liquids in other constant level containers. A sensitive air pressure switch opens a solenoid valve when the liquid level drops approximately 1" and closes it when the liquid level rises back to its original level.For automatic replenishment of evaporated liquid and liquid level control on multiple tanks, sumps or reservoirsSafe low voltage operationAutomatically turns off in the event of a power failureLonger membrane & filter life5 feet of Remote sensor tubing provided (custom lengths available)Additional switched 24 volt AC outlet for controlling booster pump or other 24 volt AC operated devicesSafety backup float