Thermometer Experiment

[gwand]

I was curious to see how much variability there might be among aquarium thermometers. The tank I selected for the experiment has a heater and a built in thermometer. The thermometer registered 75.1 F. I then placed two identical mercury aquarium thermometers into the tank right next to each other, and both next to the heater with the built in thermometer. One mercury thermometer registered 74F and the other registered 78F. Then I placed a switch blade thermometer, the kind you might use in the kitchen when checking the temperature of a roast. It registered 76.1F. Now tell me which value is correct. We have a 4 degree range in readings.

 

[Back in the fold]

You want to know if aquarium thermometer’s vary ? They most certainly do ! I have a dozen or so of those cheap glass floating and standing thermometers and they vary five degrees from each other . Most are Penn-Plax made in China ones . I think the inaccuracy is from how the paper gauge is tacked on at the factory because I can see how it isn’t the same from one to another . I keep two in each aquarium and split the difference . There must be better ones out there but the pet shops I go to don’t have them .

 

[Magnum Man]

look up calibrating a thermometer...
then find one that is adjustable... a lot of those pocket "roast" type have a nut under the dial, that allows you to make adjustments... once you have calibrated a thermometer, you can check your others against it...

I don't personally believe they are that important but if you really want to know, you have to either buy a certified thermometer, or calibrate an adjustable one

I used to have to pasteurize, and for food safety, your thermometers must be accurate...

 

[Rusty_Shackleford]

I use an IR temp gun.

 

[Magnum Man]

as do I, but those can be just as far off, as any of the others, often even more, because of the variable distances the gun is held at...

 

[GaryE]

I used to buy the floating ones. I'd go to the store and line them up. Usually, there would be 3 or 4 out of 10 with the same number on them. The others? All over the place.
I also have a digital pair with probes, and they are the same in the same tank. When I bought them years ago, they weren't cheap, and they seem good. I also had a box of the oval small ones that stick on the tank, and they were, uh, creative. You couldn't trust them.

Since I rarely keep fish that need heaters, I go by room temperatures, and use an infra red gun to confirm. I have 3 digital room temp devices and the gun is consistent with them.

 

[Rusty_Shackleford]

For those of you with a thermometer you can calibrate, how do you do it? What's your "known temperature" to calibrate to? The only thing I can think of off the top of my head is boiling water.

 

[gwand]

Ice water too? But boiling point of water varies by elevation.

 

[Ceez]

I was curious to see how much variability there might be among aquarium thermometers. The tank I selected for the experiment has a heater and a built in thermometer. The thermometer registered 75.1 F. I then placed two identical mercury aquarium thermometers into the tank right next to each other, and both next to the heater with the built in thermometer. One mercury thermometer registered 74F and the other registered 78F. Then I placed a switch blade thermometer, the kind you might use in the kitchen when checking the temperature of a roast. It registered 76.1F. Now tell me which value is correct. We have a 4 degree range in readings.

https://www.amazon.com/Digi-Sense-C...9505&sprefix=certified+thermom,aps,177&sr=8-1



I have bought 2 of these. They come nist certified with a certificate. Theyre fairly cheap considering at $40.00. Using this when checking my heater temps has been within half a degree +/-.