FastUno,
The ACJR was calibrated to a NIST traceable temperature and should be within +- 0.5F. You can always adjust the temperature offset up or down in the setup->temperature setup menu, if you don't believe the accuracy of the numbers. I personally don't put much stock in the thermometer you posted a link to. If it is anything like the floating thermometer that I've had in the past simply turning it upside down would result in the paper with the temperature scale moving about 1/4" and a couple of degree variance in temperature reading.
mozdaman,
I don't recommend calibrating the ACJR temperature to 32F with ice. First this 50F away from the temperature that you are interested in measuring and 32 is outside the operating temperature range that the ACJr is designed to work.
You don't want the temperature readings to react too quickly to temperature changes. The Jr temperature probes reacts much faster then any temperature changes that occur in your tank. Slower response helps filter noise, and adds hysteresis.
If you are seeing changes in the AquaController's temperature relative to other probes, then it is caused by some external factor:
- Temperature probe too close to heater.
- Temperature probe too close to chiller output.
- Temperature probe directly under high intensity light (localized heating)
Curt