Thermometer problems

So I have a coralife digital thermometer and it reads my tank is about 77.4 degrees which matches one mercury thermometer I checked it against. My problems is I have two floating mercury thermometers that read my tank is about 83 degrees.

Im going to go get a infrared gauge to verify what the temp actually is, what do you guys use for a temp gauges?

 

I used to 2 of them, they would always have a difference of 1 degree from each other so I would average them. Then I got a Reef Keeper Lite and the probe from it showed like 2.0 to 2.5 degrees hotter than the Coralife ones?

 

IMO they are junk & this is a constant complaint of others. The temp is not accurate as I have one as well, but use it to get a rough idea of what my SW is when I make it. I use a surface mounted thermometers for years & do what I want. They are inexpensive as well..

 

Yea I had a expensive Snap-on digital temp gauge, had 3-4 different fittings for what you were trying to measure the temp of. It was older from my dad and recently gave up the ghost. May see if Snap-On makes a newer model.

 

Ok so I checked it against a good Fluke infrared and Taylor thermometer. Good equipment. Turns out my tanks has been at about 85 :I POS Coralife. Turning everything down as we speak.