All My Thermometers Are Reading Different!

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madelyn anne

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As you can see, my digital thermometer is reading 85.6-85.8, the white thermometer is reading 82, and the glass thermometer is reading 80.

That’s a big variation.

What do I do?! What thermometer should I trust?!

Help!
 
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DaleM

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Hello hello!

Not uncommon for thermometers to show different temps, especially the cheap, analogue thermometers which aren't terribly accurate. Or take an average of them all

I'd be more inclined to trust the digital thermometer. Usually it will give you an accuracy reading on the packaging - they are usually in the realm of +/- 1f.

Where is the probe located for your digital? If it's in a different part of the tank, then you can expect some fluctuations compared to the others
 
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KakeHugs

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Hi! The glass thermometer actually seems to be reading 82!
I trust those guys more than the digital but some people like the digital better
 
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madelyn anne

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Tested it on my other tank (Ferguson is saying hello!) and getting this;

Digital: 79.5
White: 76
Glass 74ish
 
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madelyn anne

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I put the probe, and BOTH thermometers right next to each other to not allow for fluctuation. Still different results. I don’t know whether to trust the digital or the analog ones! The digital one says “accurate to 1 degree Celsius” - the glass thermometer is one I got from Petco for like $1.99, the white one was $3.99, the digital was like $11.00. For the price it better be accurate!
 
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DaleM

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madelyn anne said:
I put the probe, and BOTH thermometers right next to each other to not allow for fluctuation. Still different results. I don’t know whether to trust the digital or the analog ones! The digital one says “accurate to 1 degree Celsius” - the glass thermometer is one I got from Petco for like $1.99, the white one was $3.99, the digital was like $11.00. For the price it better be accurate!
Yeah that's why I tend to trust the digital ones more as they have accuracy claims on them, nearly always +/- 1c. In my Science degree analogue stuff was heavily frowned upon due to inaccuracies in measurement and in reading.

Easiest way to check is to put the probe in boiling water (just check on the packaging if it can handle boiling water) and if it reads 100c or the equivalent in f, you know it's accurate. If it can't cope with boiling water, try ice water and see if it gets somewhere around 0-1c. Most aquarium probes can't cope with temps above about 70c, so the ice water trick is probably the best

Hello Fergy!!!!
 
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madelyn anne

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KakeHugs said:
Hi! The glass thermometer actually seems to be reading 82!
I trust those guys more than the digital but some people like the digital better
The glass one is the one on the very right, I was seeing just below 80. The one in the middle, the white one, was reading 82.

Either way, I'm so confused!

Thinking I'll take my 3 to Aquarium Co-Op tomorrow and see if they have a really reliable one I can test these with. Or, as Dale said, I could try the ice water thing!
 
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KakeHugs

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madelyn anne said:
The glass one is the one on the very right, I was seeing just below 80. The one in the middle, the white one, was reading 82.

Either way, I'm so confused!

Thinking I'll take my 3 to Aquarium Co-Op tomorrow and see if they have a really reliable one I can test these with. Or, as Dale said, I could try the ice water thing!
Yes I know which one is glass.
I personally don't trust the digital one and the only way to figure it out is to test it against another one like you plan ):
For $11 Id hope the digital is the correct one
 
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misfittoy

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I have the white one and it reads at exactly the temp my heater is set at. If you average them all you seem to get right around what the white one is reading.
 
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