I have one, and to be quite honest, I never use it; the reasons being, the suction cup came off the glass quite often, would drift to the filter area, if there was a slight gradient change in temperature, even to the degree, an alarm went off. An alarm goes off if ph changes as well, so you can imagine how annoying this became. (the ph changes were not significant, and according to my water testing kits, there were no problems! It was very difficult for me to figure out how to program the darn thing as well, me my boyfriend and his old boss at the pet shop could not figure it out. Perhaps there is a website devoted to it, I just gave up caring and stuck to my submersible thermometer. It was hardly a bargain at 35.99 canadian dollar, but we did get it for free. If anybody wants it, let me know. Maybe someone will have better luck than I did!