Anyone have a good brand of digital thermometer? I have my reef keeper which is right on based on a glass thermo but I have 5 or 6 of the different cheaper ones. Corallife, no names, zoo med, Lifeguard. And they are all different. The Lifeguard (the most expensive at about $30) is +7 degrees! The others are all plus or minus 3-4 degrees vs. a basic glass/mercury thermometer. Crazy! Was trying to check the temp on my saltwater water change barrel and used 3 different ones to get 3 different readings. Finally went with one that I knew was 1 degree above what the glass one said to get a good idea!