Mobile Bay Reef Keepers

I am having thermometer problem. I have a Lifegard digital thermometer. I looked at the temp one day after all my lights were on for a while and the display was reading 88.6 degrees. Well of course I freaked out and turned all the lights off. I put my hand in the water and it didn't even seem warm. I turned my heater up from 79 degrees and I only had to turn the dial a couple of degrees until the heater came on. So I cleaned the probe of the thermometer in vinegar overnight and it still reads wrong. I got a mercury thermometer and it reads about 80-81 all the time when the digital thermometer reads 79-92 degrees. I have only had this thermometer for about a year so it didn't last very long.

So, what thermometer do you use and how long have you been using it?

I use the temperature probe that came with the Neptune controller, but I also have a mercury thermometer in the sump. Sort of a cheap way to double check the temperature probe.

You know personally i after all this time of having different thermometers i just bought 3 mercury floating thermometers from Wal-Mart and found that all three read the exact same temp. I am just going to lay my trust in those to tell you the truth.