ph calibration problem

[Brians947]

Hi there,
I'm having a slight problem with calibrating the ph probe. I have gone through it as described. To check if calibrated correct i check the probe in the solutions. In the 9ph solution its ok just moves up and down slightly. In the 7 solution it reads the same as the 9ph solution. It doesn't drop down to 7. If i put probe in tank it shoots up to 10.5 and stays there.

[Matthias]

to options:

- probe (resp. cable) broken
- wrong calibration proccess, the same fluid used 2 times

[funkyaneurysm]

Hi Brians,

Did your ph probe issue work out?

I'm having an identical issue with a brand new probe.

With mine, after a day in the tank, the ph reading has now dropped to 8.9. Wait, it's now 8.66. I'm 100% sure the ph is not actually changing so I'm wondering if there is an issue with the probe needing time to 'settle in'?

Was your probe new?

Thanks,
Andrew

[GHL Support]

What does your probe show in the calibration fluids after calibration? A deviation of +/-0,1 would still be ok.

[funkyaneurysm]

Hi Carolin,
I'll test the readings in the calibration fluid when I get home from work.

The probe's readings of the aquarium water, over the past few days have steadily reduced from 10.5 down to a more accurate swing between 7.99 / 8.03 (it changes every second).
GHL Control Center states calibration data as;
ADC1: 706
ADC2: 700

I'll test the readings in the calibration fluid when I get home from work.

I hope this also helps Brian if his issue was not resolved.
Andrew

[Gunther]

The ADC values are too close together (should be is someting like 400/750 for fresh water) so the probe has reached its end of life and should be replaced.

[funkyaneurysm]

Hi Gunther. Thanks for your reply.
The probe is brand new. I've had it for only a few weeks and it has been in the tank only a few days. Could there be another explanation?
Thanks,
Andrew

[Gunther]

Could there be another explanation?

If you have calibrated the probe with the right settings and the correspondending fluids as shown in the PL, there is no other resume possible as a broken probe.

Only other possible reason for this ADC values is to use the same calibration fluid for both values by error (as said above).
Your said

In the 7 solution it reads the same as the 9ph solution.

which points in the same direction. So check your solutions

[funkyaneurysm]

Hi Gunther.
I just ran another calibration with the following results;
ADC1: 716
ADC2: 714
The reading in the 9ph solution is now swinging between 9.03 and 8.91 (changes once a second to a value between those values)
The reading in the 7ph solution is now swinging between 6.90 and 7.04 (changes once a second to a value between those values)

... as I've been typing this the reading in the 7ph solution has continued to fall steadily. It's now at 6.04.
5.99
6.11
5.98
6.03
6.00
5.95
6.07
etc.

I'll contact my retailer for a warranty return. Thanks for your help.

Brians, I'm not sure if you've read any of this, but thanks for your help with the original post too! I hop you got your problem sorted.
Andrew

[funkyaneurysm]

Ironically, now that the probe is back in the aquarium it's back to showing 10.50. It has been stuck on 10.50 for the past few hours. That's how this started. That's how I found Brian's thread to begin with!