Water Refill Genie ATO KIT Works for any aquarium setup whether it is reservoir based pump / gravity fed or direct RO filter machine fed setup. Water level in reservoir can be higher than sump or tank without causing siphoning issues like other ATO products. Magnetically coupled for ease to install Water Level Sensor with no moving parts that is much more accurate, durable and dependable than float switch, optical, air pressure differential, temperature, E-field and digital based sensors! User friendly Genie Computer Unit offers 8 modes of operation to fit your need including PAUSE for tank maintenance. Failsafe features: stop & alarm you when reservoir low, pump or solenoid valve fail, tank leak or blocked overflow.