The float activated plug can be used in many different applications. If you have a protein skimmer overflow catch tank you can us this to shut off the skimmer when the catch tank gets full. This will eliminate those messy overflow situations and you won’t have to clean up smelly foam when life gets in the way and you forget about your skimmer. It has a standard grounded electrical plug so you can hook it up to practically anything; sump pumps, booster pumps, reactors, power heads anything you would want to turn on or off at certain water levels. This is great for making things “fail-safe” and worry free.