The Aqua One AquaFill Automatic Top Up Unit is designed to maintain a stable water level in your aquarium or sump. In marine aquariums, this automatic top-up system helps maintain stable and consistent salinity levels by providing small amounts of replacement water as evaporation occurs. The unit features a 3 float switch system for reliability, preventing damage to the top-up pump if the reservoir empties. It helps maintain a stable water level, includes a pump, and has a 3.5W power consumption with a flow rate of 200 LPH. It also comes with a 1+1 year guarantee.