How accurate are the stick on thermometers?

[new2betas]

Ok....to make a long story even longer...my two female betta tanks have the stick on thermometers (on outside of tank) as do most of my tanks except my hospital tank for my daughter's male betta right now.
Since he got tail rot (possibly due to temp fluctuations) I started getting worried about my female betta's temperatures. Their temps ranged around 78 during the day and would drop to around 76 at night (according to stick on therm). While I was at the lfs yesterday I picked up some of the small submersible heaters for their tanks (one is in a 2.5g and one is in a 2g). I also have one in the hospital tank. I put the heaters in yesterday afternoon and the temp came up to 78-80. They seemed very happy and content....no problems.
This morning I get up and look at their temps just to check and the readings on the stick on thermometers were reading 80 in the green with 82 a tan color. That kinda freaked me out and I was scared they could be cooking so I took the heaters out of the female's tanks and took some water out and added room temp water. I then checked my male bettas temp who is in a 1.5g hospital tank, BUT he has the submersible in tank thermometer. His temp was reading right on 80. He is in a smaller tank than them, with the exact same kind of heater and his water was reading right at 80. So, which of these thermometers is wrong?
Also, for tanks 2.5g or less, do they make heaters that will turn off if the temp is reached....I can't find them anywhere. Even online I only find those really small flat heaters for smaller tanks, but they don't have a thermostat in them. I will really need something for winter time that can be trusted.
Sorry this was so long.....

[Korwin]

You could always put all the thermometers in one tank as a little experiment. Then you can see what they read when they are in the same water.

Also, I don't think most of those thermometers are very accurate. BUT, the important thing is consistency to avoid those fluctuations.

[new2betas]

Originally Posted by Korwin

You could always put all the thermometers in one tank as a little experiment. Then you can see what they read when they are in the same water.

Also, I don't think most of those thermometers are very accurate. BUT, the important thing is consistency to avoid those fluctuations.

Korwin,
The only thermometer that I have that goes in the water is the one in the hospital tank that my daughter's male betta is in. The other ones are stuck to my female betta's tanks. I can removed the one on one of my female betta tanks and place it on the outside of the male betta's tank and see if they are the same, I guess....

[new2betas]

I just took the stick on thermometer off of the female betta's tank and placed it on the hospital tank (which is reading 80 with an internal thermometer). The stick on reads 82 on his tank....so which is correct??? If it really is 82 I need to take out the heater, that is too hot. But, he seems to be acting fine.

[Fishyfanatic]

Toss the stick on thermometers. They do not measure the temp of the water, they are measuring the temp of the glass. Get a thermometer that goes inside the tank. Digital or a glass thermometer.

[new2betas]

Thanks fishyfanatic! So, you think the thermometer that is floating in my hospital tank is the more accurate one (it is glass)? I guess I will be tossing all of my stick ons now...which is about 6 of them....geeeeezzzzzz.

[meegosh]

I agree to disagree. I found that my floating thermometer was reading like 85-90 and I found it hard to believe. I went out and bought a digital thermometer and sure enough the water was 76 like it should have been. I was curious about my stick on thermometer on my 10gal and I put the digital in it to see how close it was. The tank was 76.6 (digitally) and the stick on was showing a light 78 (when its lighter I take it as being on the lower side of what it says).

That's not to say that all stick on ones are accurate. When my AC kicks on those things give crazy readings. I picked up my digital one for $11, best money I ever spent. I can get accurate, and quick readings in both tanks and when I'm doing PWCs.

Hope it helps

[new2betas]

Originally Posted by meegosh

I agree to disagree. I found that my floating thermometer was reading like 85-90 and I found it hard to believe. I went out and bought a digital thermometer and sure enough the water was 76 like it should have been. I was curious about my stick on thermometer on my 10gal and I put the digital in it to see how close it was. The tank was 76.6 (digitally) and the stick on was showing a light 78 (when its lighter I take it as being on the lower side of what it says).

That's not to say that all stick on ones are accurate. When my AC kicks on those things give crazy readings. I picked up my digital one for $11, best money I ever spent. I can get accurate, and quick readings in both tanks and when I'm doing PWCs.

Hope it helps

Thanks meegosh...it does help. So, how do the digital ones work? Is it something you hold and put in each tank to test the water or is it something that floats in the water?

[new2betas]

Nevermind...found it...lol
Little Time or Temp Digital Clock/Thermometer - Heating - Fish - PetSmart

Could you use this in more than one aquarium....meaning could I take it out and test each aquarium individually when I want to know what the temp is instead of putting one in every aquarium that I have...that would get really expensive fast!

[Fishyfanatic]

Yes, you can definitely do that Dottie. I have used the glass ones with great success in addition to the digitals.