Looked at my apex when I got home and my two temp probes are in disagreement. I had two so I had a backup if one failed, but what do I do when both are acting up? Any advice?
Get a temp strip and attatch it to the side of your tank. You will be surprised how accurate they are.
Mine reads the same as my aqualogic controller, Hanna monitor, and my old mercury thermometer, lol.
I have used an old mercury for years as a backup. I have several but my one that reads from 66-80 is my favorite.