tank temp

Eric, get a cup of ice and mix in a little fresh water. It should be 32F with the laser. Then boil some water and point it at that...212F. You'll know if the laser one is calibrated.
(Adjust for altitude, those are sea level freezing and boiling points...don't want to get called out on that by someone who lives in Denver, Co.)

 

Ha, Ha...Been there..

To feel really confident about temperature measurement, I have about 4 different kinds of thermometers...

Digital ones are least reliable. Always crosscheck with something else!

Good luck!

 

Then you have a problem with the thermometers. You could return the units you have and get new ones, or just know that they are off and make a mental adjustment when you read them. If it was me, I'd be getting a new one until I found one that read right. But I'm picky like that...

 

are the glass ones more reliable?

 

I have 4 glass thermometers. One in each tank, and 2 spares (just accumulated them over the years). I just took all 4 of them into the kitchen and let them sit for an hour. Every one of them reads the exact same temperature, so I'll say I'm partial to the glass ones. I've also read, many times, that the glass ones are more reliable (even if they are cheaper). My 2 cents.