I built this leak detector using the io breakout box. Couldn't be any simpler. Just a couple nails, solder, wire, piece of paper towel and masking tape. Works with SW and RODI water. When the paper towel gets wet, it closes the switch on the io breakout box, which you then reference in your programming. I use it to shut down my return pump. But you could tape it to the side of your skimmer, or wherever, and shut off (or turn on) anything that is connected to your Apex.
