I got a tank with a stick on digital thermometer (one of those strips) which I thought was working pretty well until the room got warm and I realized it was giving me the temperature of the room, not the temperature of the water. I bought some cheap floating thermometers with suction cups at the LFS and those work OK. But, they're kind of hard to read with my old eyes. Then, I found this on Amazon.com I ordered one just to try it since I have three tanks and the price seemed too good to be true. I've only had it a few days. But, it works, it seems to be pretty accurate and it's really easy to read. The probe has a suction cup and the display can be stuck anywhere on the outside of your tank. So, you can make it virtually invisible.