ph probe problem Apex

[ltelus]

This morning i noticed ph probe 1 swing a little so i went out and picked up a new probe.
I have had problems calibrating the new probe,its a DA probe(i know, i know:rollface:) the calibration numbers seem in range for 7 calibration but don't seem to change when i go to 10 solution,they still settle in the same area as when calibrating with ph7. I know the numbers are not really relevant but this does not seem normal. I have calibrated the new probe several times and when i put it back into my system it either reads around ph 6 or 9.5.
I recalibrated my old probe but am getting the same result.
I have also had a calibration failed message after calibrating some times also.
I have checked my ph with a hand held it it reads right where i expect it around ph8

PH2 in my reactor seems to be working fine


Any ideas
TIA ,Liam

[kenargo]

You are correct that the calibration numbers are not representative of a real reading but you should still see values (during calibration) 'in the neighborhood' of the calibration fluid and if not then it would be an indication that either the probe of fluid is bad.

Once calibrated it is always good to 'test' the probe bu placing it back in each fluid and you should reave very close to the correct value.

What you describe suggests a bad probe; which is possible is the probe is sensative at the calibration points but non-linear in the middle but I'm guessing. It's odd that the other probe would not calibrate; PH probes are pretty standard.

Have you tested the probe back in the calibration fluids? You could also try some common house liquids and see if they show correct; it could be your calibration fluids.

[ltelus]

i forgot to mention i tried 2 differrent sets of fluid also.
When i return to apex home screen after cal,the probe is reading 10 exactly before i rinse it in ro/di and return it to the sytem where it drops to around 9.4.
I also tried a restart and complete power down.

[ltelus]

I am tending to agree with you Ken,i believe the interrmittant problem with the old probe is coming into play.
I got the old probe to calibrate and will return the new probe tomorrow.
I will update here after trying another probe
thanks

[ltelus]

just to conclude this thread it was indeed a case of 2 bad probes.
I picked up a new probe today and all is well.
I even gained + 0.02 on my ph reading which is a nice bonus:thumbsup: