PH calibration issue

[tmccaf]

I tried 2 times to calibrate the PH probe the fiest time I got 3.5 as reading and now 10.5.

MY ADC Values:

ADC1 Value 1023 ADC2 Value 1023


Do I need a new probe or is there something I can do to fix this?

[Vinny]

First, make sure you have the probe connected to the correct port, pH / Redox
Second, make sure you are calibrating with the correct fluids, pH 4 and pH 7 (freshwater) or pH 7 and pH 9 (saltwater)

Steps for calibrating this probe can be found here:
https://www.aquariumcomputer.com/knowledge-base/how-to-calibrate-the-ph-probe/

[tmccaf]

I will see if I am connected to correct port; I am using PH 7 & 10 that ok for saltwater?

[Vinny]

Yes.

[tmccaf]

Yup it was plugged into Redox/Ph port; I guess need to recalibrate as well now.

[tmccaf]

Also I got same calibration fluid from GHL the other day no expiration dates; they no longer?

[tmccaf]

I feel dumb it was put in wrong port; recalibrated and now working correct. On the conductivity probe is it normal to have a big difference in what the probe says and my digital refractometer? I may have done calibration wrong on it. What is calib tolerance? 1, 2, 3 do?

[Vinny]

If you are using the kg/L unit on the P4 and SG on your refractometer, the reason for the difference is because kg/L and SG are not equivalent to each other.
1.025 kg/L does not equal to 1.025 SG

You can use a calculator like this to convert kg/L to SG:
https://www.hamzasreef.com/Contents/Calculators/WaterDensity.php

You can however use the PSU unit for your conductivity probe as this is equivalent to the PPT unit shown in refractometers.

Calibration tolerance information is explained in the P4 manual.