I also use the Digi Coralife with the probe mounted in the bottom of my overflow. The only thing with these are that their not precise. +/- 1.5 degrees F, that's not that accurate when it comes to reef keeping. I also use one of the small glass style thermometers with the suction cup. I just remove the cup and let it float around in my sump. More accurate than the digi but I like the convenience of the digi on the side of the tank.