View Full Version : Temp probes not accurate

02/03/2017, 03:23 PM
I was told u never have to calibrate them. I have bought 2 thermometer and both of them are pretty accurate to each other but I have 3 tanks 3 temp probs and 2 of them are off pretty good from the thermometers. I only found this out cause lately my lights have been off from high temp but tank doesn't feel hot so got the thermometers. They say 79.5 ish and the apex is over 82 on that tank. The other tank never reads over 76 but the thermometers show over 81.

These are very far off. Should I just calibrate them or get new probes? One of these is only 6 months old or so.

02/03/2017, 03:50 PM
I doubt it's the probes.

02/03/2017, 04:03 PM
I doubt it's the probes.

So just calibrate them?

02/03/2017, 04:19 PM
Most aquarium thermometers are very inaccurate. I have found variances of 4 or 5 degrees on some. Your apex can be calibrated for accuracy. If you want an accurate thermometer to set your apex to, I would look outside the hobby suppliers. A good thermometer will say how accurate it is. The few aquarium thermometers I could find that said were only accurate to plus or minus 2 degrees. So if it is reading 78 it could be 76 or 80 degrees.
I picked up a digital temperature probe that was rated at plus or minus .2 degrees online for under $50.00 a few years ago. That is when I really realized how bad aquarium thermometers tend to be.

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02/03/2017, 05:26 PM
I have this one from Lamont should be good then I have a cheep floating one. Both these r accurate to each other. I calibrated the temp probes on the apex so we will c. Who knows what is right but apex was def wrong. U can tell just by touch the tank is not 75 deg. And the one that says almost 83 is not 83.

02/03/2017, 06:13 PM
I keep an Apex Temp probe in my sump and one in my tank .
Calibrated both of them in the tank,
I redo the calibration every 2 months or so.

02/04/2017, 04:05 PM
Isn't precision more important than accuracy .... well within reason?

02/08/2017, 01:40 AM
Isn't precision more important than accuracy .... well within reason?


My second probe isn't precise at all. In fact I believe it's actually the PM3 module and not the probe; regardless whether I switch probes - it always exhibits the same behavior when connected to PM3.

02/08/2017, 02:45 AM
I'm starting to think the same thing. I calibrated mine but the 2 of them on my pm1 are still doing weird things reading wise