I've been trying to solve for this myself. I have a floater and I don't like having to look around for it in a different place everyday, or dig it out of the skimmer. Sinking one is a good idea, as I don't really need to know the temp of the top 6" inches! I've toyed with the idea of drilling a hole into the tile, or just under the coping and using some sort of nylon bolt or something, even if I had to epoxy it in, as an anchor for a tether. That's as far as I've gotten...