Little help with acurate thermometers

[stany]

I have three identical mercury thermometers by brand and type that give me different readings when placed in the same tank by 2-3 degrees. I can deal with the differences in setting up the heaters if I know the true temp.. Looking for suggestions on a meter that is accurate and can help me calibrate my heaters to the desired temperature.

 

[Carolineep]

I went with a Infared because I was having the same issue.
Although now it's warm enough and stable enough I have most of mine unplugged or on the lowest setting for my fish that love the heat.

You can pick them up at Home Depot or online. Please let me know if yoo find an accurate mercury one.

 

[mchambers]

Like Caroline, I use an infrared thermometer. You only need one, and it's accurate enough for fishkeeping needs.

 

[Frank Cowherd]

Depending on the range of your thermometer, a mercury thermometer can be calibrated by sticking it in boiling water where the temperature should be 212F or 100 C.
In ice water with crushed ice and little water the temperature should read 32F or 0 C.

But often a mercury thermometer can have a split in the mercury column. You have to check closely the whole column. If it has a split or gap, it is off on the high side by the amount of the gap. Sometimes you can repair these thermometers by placing them in dry ice which will suck all the mercury into the bulb. Then let it warm very slowly in an upright position and the gap should be gone.

But for the most part a difference of 2 or 3 degrees is not significant in the aquarium and will not likely have a noticeable affect on the fishes behavior.

 

[stany]

I have a 5 degree difference between the three if I put them in the same tank. Think I'll invest $30 in an Infared and mark each mercury with a line with that setting. I got spooked dong a water change when I pulled one of the heaters in my community tank and the temp in the bucket of water to use for the change read 87 degrees. It was in the sun which may have caused some of the problem. The Infared will give me a baseline, let me check for air leaks around the doors and windows and detect any paranormal activity. Thanks everyone.

 

[chriscoli]

Love my infrared thermometer. I used to steal Bruce's from the kitchen all the time....so I finally got my own. Sometimes there's a good sale on the ones from Harbor Freight if you happen to have one of those near you.

And like you said, I use it around the house all-the-time! Especially in the garage if I'm overwintering plants and want to know how close to freezing things are getting. I'll adjust my plants on the garage shelves according to temp.

 

[FishEggs]

Just got the July Harbor Freight sales flyer and there's a coupon in it for the IR temp gun for $20. There are some cheapo brands available on Amazon for about $15.

 

[stany]

I'm going to Home Depot Monday to pick one up, No Harbor Freight near me.