ACIII Temp probe calibration

[[WDT]TardFarmer]

I just picked up an ACIII. When I put the probe in my sump it began reading temps in the high 80's I believe it said 88 degree's. Well I touched the water and it certainly did not feel that warm. My cheapo coral life digital thermometer said 77.8 degrees. So I calibrated the ACIII temp probe and dropped it down to 77.8 degrees. Well now it is reading at 72.8 degrees. My corallife is reading at 76 and I dropped in a glass thermometer which says 78 degrees.

Question is how do I calibrate this correctly? I called Neptune systems who just told me, "we calibrate them within +/- .2 degrees, find something to calibrate it with....". I asked repeatedly what but never got an answer.

Anyone out there have an idea for me? I thought about ice water which should bring the temp down to almost freezing. So I tried a cup full of icewater and let both the ACIII probe and the corallife sit in there for about 10 minutes and it registered at 35 degrees on the corallife. I can't remember of the top of my head what the ACIII was at.

[Hiren]

I've heard both ways on the cheapo Coralife digital probe thermometers - some are very accurate, some are notoriously inaccurate. I've heard stories of inaccuracies up to 8 degrees or so. Problem with them is they can't be calibrated.

The ice water trick is great for calibrating. It's not surprising your Coralife therm is 3 degrees or so -- just keep that in mind when you're using it. Calibrate the ACIII to 32.2 or so after sitting it in the ice water if it measures that low - my ReefKeeper doesn't go that low...

But if you know your Coralife is off by 3 degrees or so, you can use that to calibrate. Honestly if you have good temperature control on your tank 1 degree isn't going to be a huge problem unless you already keep your tank on the high end of the temp spectrum for your livestock.

(Note: I have about 3 Coralife thermometers and have a note on the back of each how far off they are. I just adjust when I take the reading)

[ANGRY JOHN]

the best way i could come up with is to use a therm that you use to check your temp. grab the one out of the medicine cab and go for it.