Which ones right lol

[Potluck]

I have a digital thermometer and a old school glass one the digital reads 2-3+ degrees higher and in trying to adjust my heater to treat my ich that's actuality going away but my tank temp keeps dropping down to 85 on the digital and 82 on the glass one so I'm getting frustrated, I have an Aqueon Pro 250 watt in a 55 gallon it's set on 81-82

 

[Andy Sager]

Hate to say it but I'd get a third thermometer and see which one that one agrees with. 2 out of 3 can't be wrong. Just make sure the third one is 100% accurate before you test.

 

[Funken_A]

my money is on the old school mercury thermometer. Electronics can never be trusted unless calibrated regularly

 

[dalto]

my money is on the old school mercury thermometer.

Me too. I have yet to find an inexpensive digital thermometer that worked accurately over the longhaul.

I also agree with Andy that you should use a third thermo to know for sure.

 

[Sandfall]

Probably the old school mercury, but I would use a third to make sure. The mercury is built in a way that should make it on the spot, but it's better safe than sorry.
One thing that you could try is taking them out of the water, letting them adjust to the air in your house, and checking them against your thermostat. If your thermostat is correct, whichever one matches will be right.

 

[skrapeNKA]

I'd be more inclined to side with the digital, but you can test it as long as you have ice! Just fill a glass with ice, top it up with water, and give it a good stir. After a few minutes, stir it again and put your thermometer/probe in the middle of the glass. It should read dead on at 32 F (or 0 C); if not, that's how far off it is

 

[Potluck]

They aren't murcury anymore from what I was told, they are lead beads, I asked this a few months ago when I had my convict break one, I did a third and the glass ones are exactly the same where the digital is 2. 5 degrees off

 

[Potluck]

I'd be more inclined to side with the digital, but you can test it as long as you have ice! Just fill a glass with ice, top it up with water, and give it a good stir. After a few minutes, stir it again and put your thermometer/probe in the middle of the glass. It should read dead on at 32 F (or 0 C); if not, that's how far off it is

Hey that's a good idea never thought of that lol

 

[subliminalme]

They aren't murcury anymore from what I was told, they are lead beads, I asked this a few months ago when I had my convict break one, I did a third and the glass ones are exactly the same where the digital is 2. 5 degrees off

Digital has always been unreliable to me. Great tips. Thanks for asking! Learned something new ☺

 

[Potluck]

Digital has always been unreliable to me. Great tips. Thanks for asking! Learned something new ☺

Yvw and I'm glad I learned something as well waste of $15.00 but I do know it's 2.5 degrees off so I can still kinda tell what the temp is though I'll still be using my glass one