Auto Aqua Automatic Top Off System with Controller & Sensor in One What is Smart AFS Technology? The Smart ATO is a unique Auto Top Off system with a patent pending contactless digital sensor that monitors and automates refilling evaporated water. Best of all it is very easy to install and contains no moving parts that can fail. This ATO comes integrated with AFS (Auto Feedback Security) technology which provides real-time fail safe protection against failure. You simply move the outside controller to adjust your sump to a desired water level. Its that easy!