Infrared Temp Guns - NECCESARY, but MUST BE CALIBRATED - Here's how!

[dakski]

Frequent contributors on this site and also those with experience who post (or both) are always talking about using IR temp guns for accurate ground temps.

They are are a must. Thermostat probes can be off and only get air temp (except for UTH where they can read off the UTH - but it's under the tank, not in the tank), and normal thermometers with or without probes also only get air temps.

If you want to know what temp your reptile is actually at, you need ground temps. This can accurately be achieved with a temp gun. They range from about $14 to $200 and you can get them at home depot, amazon, etc.

Here's the thing that many people do not know! YOU MUST CALIBRATE YOUR TEMP GUN and pretty much every time you use it.

Temp guns, can be off, and may not give you an 100% accurate temperature.

First, a few rules for using an IR temp gun:

1. Calibrate the temp gun before use (see below for instructions).

2. Try to shoot the IR beam straight down from the where the beam comes out of the temp gun. Don't do at an angle, or far away either. Try to put the temp gun with the beam facing straight down close to and with a consistent distance from the area you want to read.

Again, consistency is key and as little angle and distance as possible. You can hit the same spot at 2 inches and 2 feet and you will see they read differently. BE CONSISTENT with DISTANCE and ANGLE!

3. When reading temps in a tank, take multiple readings in each zone throughout the temp gradient (hot side, ambient, cool side). It takes about a second to get an accurate reading. My tanks are mostly 6X2's and I get 3 readings on the hot side (bang, bang, bang - front to back), 3 in the middle, and 3 on the cool side. It takes about 15 seconds a tank to do this. Heat tape, UTH, etc. can create different contact points and different temps (slightly) throughout them. For example, in my BP's tank, she has a RHP and Heat Tape on the hot side. The tank is 2FT deep and the heated area about 1-1.5FT wide. I hit the middle of that zone at the front of the tank (not under RHP) and it reads about 87F, in the middle it reads about 88F, and in the back, fully under the RHP and over the heat tape, it generally reads 88-89F.

4. Always take multiple readings in each spot, especially when first using the temp gun.

You can hit spot A when you first use the gun and it can read 82F. 2 seconds later you can hit the same spot at the same distance and get 78F. Not sure why, but it my experience, temp guns can need 2-3 "shots" to dial in. Once I've used a few times, it seems to be ready to go. However, first pull with my gun(s) often read much higher than they do 2 pulls later. When I get a consistent reading; 77F, 77F, 77.3F, etc. I know it's ready to roll.

​How to Calibrate a Temp Gun:

Calibrate that temp gun by shooting the beam at your room thermostat (or reliable thermometer) and adjusting accordingly.

If room thermostat reads 70F and the temp gun reads 71F, subtract 1F from whatever reading you get from the temp gun. Shoot the thermostat at the same distance (as close as possible) as you shoot the ground of the enclosure. Try to keep the beam as straight as possible (up/down) and avoid long distances or angles, if possible.

This works conversely if the temp gun reads low. If the room temp is 70F and the temp gun reads 68F, you would add 2F, instead of subtracting.


Why do I have to do this?

Simple, and again, temp guns can be off and can vary by how much. You need to know on that day how off (literally in degrees F) your gun is that day.

I have an $81 Raytek MT6. Top of the line temp gun. It consistently reads 3-4F high. Before using it, I hit a reliable thermometer in my house. Today, the thermometer read 72.5F in the reptile area. I hit it with the temp gun and the temp gun reads 76F. When I shot in the tanks today, I subtracted 3.5F from each reading.

In other words, 93F on my BP's hot spot, is really 89.5F (93-3.5F).

It's very important to calibrate so you do not overreact and make adjustments that aren't needed, or too drastic an adjustment, to your reptiles temp.

Also of note, when adjusting temps, do so very slowly. Adjust thermostat (MANDATORY ON ALL HEATING ELEMENTS) 1F at a time, or at most, 2F.

Why get an expensive temp gun?

I am not sure. I paid $81 for mine and it's consistently off. However, it's consistently off by 3-4F (reading high). Maybe I paid for it to be consistent at being off?

We also have a $14 temp gun for Esmeralda, our Leachie, who lives in Katies office and temps are not as important to her since she lives happily at room temp.

Today it was off 2.5F. Who knows?

Frankly, if you calibrate properly, and before use, you should be good to go with any IR temp gun, IMO.





Please feel free to add to this thread and/or comment.

This is my personal opinion from using temp guns for years and owning 8 reptiles in 7 tanks currently (plus Esmeralda - who technically is Katie's) and keeping reptiles for over 20 years.

My hope is that this helps keepers to use temp guns and to use them properly.