Temperature Discussion

You are right on. If you want to test water temps stick the gun into the tank ( above the waterline) It wont be a real solid reading, and you are better off with a temp probe on a multimeter for the most accurate readings.

A gun can give you a cursory look at where abouts your tanks sitting. And I have one on each tank that I shoot in the morning for an idea of where things are, but you certainly cannot hit the glass for a temp. The glass will be a reading of what you were talking about. a mixture of the ambient air temps and the water temp when transferred through the glass.

 

Yeah, Again the guns are good for an at a glance. the only way to get a solid water column temp is to take a temp across multiple points in the tank and average it out. from both low and high in the tank and near dead spots.

Are you having trouble with temperatures in the tank?

What type of lights are you running, and are you running heaters in this season?

 

Put some PVC in the tank for a while, remove and test. Water is an amazing heat conductor, Not likely to see any meaningful difference in our tanks other than directly in contact with a heater or external exchange ( the glass).

 

The reflective and emissive characteristics of glass aren't going to help. In my mind, glass is not very close to a "black body" so it's going to be hard to get a good reading on it. Also, the temperature gun reports the average temperature of what it can see and that depends on the distance between the gun and the target. If you stand too far away from the tank and try to take its temperature you'll get an average of the tank and some of the area around it.