Thermometers

[Essjay]

The heater in my main aquarium stopped working and the replacement arrived yesterday afternoon. I also bought a digital thermometer, the kind with a probe which sits inside the tank and the display outside the tank.

I've always used the ones with the liquid inside that stick to the inside of the tank with a sucker but got fed up with replacing them when the suckers stopped working and the the thermometer just pirouetted round the tank and couldn't be read. I also have 3 thermometers of the long thin type - one for the new water at water changes, one in the kitchen from when I had a breadmaker and needed to check the temp of the water, and one in the bedroom for the summer for when it gets too warm for my eye drops. My husband also has a digital thermometer in the room where he keeps his violins and violas.

Once the new heater arrived I set the dial a bit lower than I want and put it in the tank together with the new digital thermometer, the aquarium long thin thermometer and one of those where the sucker no longer works. None of the thermometers gave the same reading. So this morning I gathered several of them and placed them side by side for half an hour. The mechanical ones are laid on a wooden trivet with the bulbs sticking out in the air, the aquarium digital has the probe suspended from a fish food tub so that the probe is also in the air, husband's digital is on the trivet.

Husband's digital - 17.4
Aquarium digital - 17.7
aquarium long - 15.5
kitchen long - 17.5
bedroom long - 17.5
'sucker' aquarium -17.0
all degrees C


The worrying one is the long aquarium thermometer. That's the one I use for the new water and the one to check if the heater is set right. So the aquarium temp has always been higher than I thought.
I have now thrown away the one I've been using for the fish tank and I'll use the kitchen one instead for the new water - since I no longer have a breadmaker I haven't used it in ages. And use the digital one in the tank.
And I've turned the dial on the heater down.



The moral of this tale is - don't trust the accuracy of any type of thermometer until you have compared the reading with several others.

 

[GaryE]

I don't worry if my water change water is one or two degrees higher than the tankwater. Lower would concern me. But thermometers and heaters are notoriously inaccurate. I try as much as I can not to use heaters - they have killed too many fish here.

In an old thread, I mentioned how I had once bought ten little digital thermometers - the same ones as are sold for a high price here. I paid about what 1.5 would have cost for 10 out of China. Some lasted for quite a few years, but if I recall correctly, 2 gave wrong readings out of the box, and within a couple of years, most had failed.

I have several thermometers set up in the fishroom, to give me an accurate room temperature. I use an infrared temperature "gun" to check water, and I can easily check its accuracy. Thermometers are one of the things I never trust without backup.

 

[Essjay]

I've been lucky, when my heaters have failed they've just stopped working, they haven't stuck in the on position like so many seem to.
I do need heaters as we don't keep the rooms with the tanks very warm in middle of winter.


I have to admit that I don't check the new water temp very often, mainly when the season changes so I know how much water to boil for each bucketful.

 

[Donya]

I don't worry if my water change water is one or two degrees higher than the tankwater. Lower would concern me. But thermometers and heaters are notoriously inaccurate. I try as much as I can not to use heaters - they have killed too many fish here.

In an old thread, I mentioned how I had once bought ten little digital thermometers - the same ones as are sold for a high price here. I paid about what 1.5 would have cost for 10 out of China. Some lasted for quite a few years, but if I recall correctly, 2 gave wrong readings out of the box, and within a couple of years, most had failed.

I have several thermometers set up in the fishroom, to give me an accurate room temperature. I use an infrared temperature "gun" to check water, and I can easily check its accuracy. Thermometers are one of the things I never trust without backup.

I’ve been wondering about getting one of those temp gun things. I’ve been ok with the variance issue for cheaper more traditional types, but am sick of my sw critters literally eating probes. Urchins are practically attracted to them as a snack. I just got a ridiculous magnet cleaner and temp reader combo device because of those beasts - it’s hideous lol but at least the probe sits on the outside of the glass.

I’ve also found the cheaper probe type ones tend to fail low - and it’s very hard to catch that hinge to know when they’re just slipping vs it being a heater about to give out.

 

[Back in the fold]

I have a thing for aquarium thermometers . I’ve got a lot of the cheap ones and the temperature they read doesn’t vary enough to be a concern .

 

[Magnum Man]

You could look up calibrating Thermometers… being from the food industry, we are required to calibrate any critical process thermometers at least annually… and you are right, there can be a huge variance in thermometers, and just because they are digital, doesn’t necessarily mean they are more accurate… I’m not breeding anything, so a couple degrees is not critical to me… but if it was, I would get a cheaper adjustable mechanical thermometer, and calibrate it, ( ice water / boiling water ), then use that to check any other thermometers I’m using in the aquariums… as far as aquarium thermometers, I’m not aware of any that are calibratable…

 

[GaryE]

The only advantage to old school thermometers is they also have fahrenheit on them, since they have US distributors here. So when I have to speak American temperatures here, I don't have to do a conversion!