So my corals have not been looking good as of late, tested my water, everything was where is should be. I calibrate my refractometer every few weeks due to it being off and causing a tank crash last year(It was reading 1.025 but salinity was actually 1.031). Could not figure out what was wrong. I put my hand in my tank(which I do not like to do) to move a piece of LR and was surprised how warm the water was. I checked the temp. with a regular glass aquarium one and the temp. was 86. My digital thermometer was actually stuck reading 78. The one of the heaters crapped out and was stuck on. So, back to the basic $1.99 thermometer for me. I guess the KISS principle applies to reef keeping as well; well for some things anyway.