... wide range of applications. A float switch is a device used to sense the level of liquid within a tank. ... hydroponics, saltwater tank, freshwater tank, gardening, aquariums for power head control, pet bowls, fish tanks, filtration, heating, pumps, ponds, ... pans, pressure washers, carpet cleaning mach., reef aquarium, fluid control, ice machines, coffee pots, marine, automotive, automobiles, tropical ...