Marine Auto Top Off (ATO) systems automatically replace evaporated water with fresh RO/DI, keeping your salinity and water level stable without daily manual top-ups. Using a sensor in your sump or display and a small pump, they add small amounts of water as needed, reducing stress on fish and corals caused by fluctuating salinity. ATO units are one of the simplest upgrades you can make for long-term stability and convenience, helping to protect your livestock and making reefkeeping far less hands-on day to day.
