two sensor ATO

Hi
I set up a two level sensor ATO with an external pump using your video. After setup I check that everything works by manually lifting the sensor a few centimeters out of the water and sure enough the pump turns on. But what happens then is I have a look a few days later and the water level is below the lower sensor i.e the ATO isn't working. this has happened 5,6 times in a month. So what am I doing wrong?
I occasionally turn the ATO on manually using a maintenance program I have setup, Just cant see what Im doing wrong.

Have you cleaned your level sensor lately? If film, detritus, or algae develops over an optical sensor, it can make the sensor think the water level is still normal.

Please post screenshots of your LEVEL sensor settings, control circuit where you have the ATO function created, and switch channels and outlets page.