The Smart ATO is the smallest and most novel water level sensor and automatic top off controller the hobby has yet seen. The magnetically coupled sensor and controller are one assembly, with a single light sensor being sent through a prism on the wet side of the assembly, inside the sump, to determine high and low water level.
At $150 for the sensor, controller, pump and plenty of hose to set it all up, the Smart ATO is the most complete and simplified ATO kit you can get. Having everything built in to such an impossibly small device makes it easy to keep the ATO system very discrete.
Setting up the Smart ATO is dead simple, and the only reason to crack the very basic instructions is to know what level to initialize the sensor-controller at. The only quirk of the Smart ATO’s function is that it has to be initialized above the water level. Otherwise, the Smart ATO just gives an annoying “high water alarm” which won’t affect the tank, but won’t let you do anything until you make an adjustment in water level.
This high water alarm is problematic during a power interruption, which we simulated, wherein the water level in the sump rises and when the power is restored, the Smart ATO gets started up below the water surface and it screeches for you to do something about it.
Other than that, the Smart ATO is probably the best Auto Top Off system for sensing water level through the walls of the aquarium or sump. With opaque white dreamboxes, and All In One aquarium filters having black walls, the Smart ATO just won’t work and you’ll have to consider other options for ATO functions in these set ups.
On size and simplified function alone the Smart ATO is the iPhone of ATO kits. Most ATO devices and systems are simple enough for regular reefers to install but the Smart ATO is definitely the kind of device we feel comfortable sending our parents home to install on their own tank.