We left over the holidays and were gone three straight weeks. The hot tub was left on, 102 degrees, and no one did a thing to it. Before we left I filled the bromine floater with 4 pellets and checked the levels (all fine). I might have shocked it but that's it. We returned and the water was perfect. All levels (including bromine NORMAL). I am puzzled as to how this could be. Does it use less bromine when no one is in it? I was thinking we'd come home to a cloudy pool of goo, but it was crystal clear, good to go. wild.