you can easily add a float valve as the 2nd sensor or even add another top off kit and instead of using to trigger a pump, you can trigger it to turn off your skimmer.I'm trying to kill two birds with one stone: set up water level sensors so I can control when my skimmer should be on and off, and set up an ATO. I've used a Tom's Aqualifter and a standard 2 float switch for 9 years with no issues, so I don't mind going back to that if necessary. The ATK allows me to do both in one setup.