... you would need to put it at. Description:A float switch is a device used to sense the level of ... liquid within a tank. The switch may actuate a pump, an indicator, an ... alarm, or other device.Use them with hydroponics, saltwater tank, freshwater tank, gardening, aquariums for power head control, pet bowls, fish ... x 107(DC 5V,10mA) FX-1AH-55-M16C Water Level Float Switch