pH probe calibration drops off after a few days

[Symbiot]

I've posted this issue at ultimatereef as well, but no one seems to have any input... perhaps it's the holiday season.. anyway, I thought I'd post here as well.. hope you guys can help!!


As topic title.

I've years of experience with pH probes, I've worked with them in my job, and feel that calibrating a pH probe is easy, and nothing to worry about.

however, after changing to af GHL profilux computer I am experiencing problems...

I calibrated my pH probe a while ago... say 2 months... then after some time, I noticed, or actually didn't notice, that my CO2 system never kicked in. The pH measured around 6.7 all the time.. it drifted a little up, and a little down.. like normal.. but it never drifted so high that the CO2 kicked in.
I checked with a normal pH meter and the pH was around 8.
I figured I needed a recalibration, and all would be well...

well no... first of all..

I calibrated the probe once... usually I calibrate a probe a few times just to check... well, the 2nd time I calibrated it, it measured completely wrong.
I tried again and again.. but to no avail.

I then thought.. it must be the calibration fluid. I got it mixed up somehow..

I redid it, managed to get a good calibration... did a recalibration, and all went to H**l again..

so, I figured.. well.. only do 1 calibration and leave it at that...


so I did...

so the probe was then running fine in the tank... CO2 was kicking in etc.. all well..

well now a week later, the problem is back.. pH sits at 6.9 and stays there.. I turned off the CO2 just to be sure the CO2 wasn't just kicking in when I wasn't looking..
well the pH shows a steady 6,9 always... it drifts a little.. as before, but it sits there...


Now to me it feels like a type of firmware issue.. but since I haven't got much experience with profilux it's hard for me to say!


Have any of you tried something similar? or have an Idea of what I should try?

 

[AQD_ottawa]

Hi

To reasure you you this is not the profilux and it is not the firmware you just have a degenerated probe, it happens from time to time, no matter what the make a pH probe can degenerate quicker than normal, this is why all probe manufacturers only offer 3 month warranties on them as they can not control the enviroment a probe is put into. The most harshest enviroment is a calcium reactor due to the probe being effected 24/7 by dissolved solids.

The other suspect will be the pH cable close to a high electrical field

There are three options here,

1. Move the probe lead and make sure it is not near solenoids or electical devises including pumps
2. soak the probe in pH 4.0 over night and then recalibrate and test.
3. Depending on age see if your LFS will replace under warranty.

Or email the UK distributors sales@ghl-profilux.co.uk

So to again reasure you this is nothing more than a probe that sounds like has degenerated a early and needs the membrane soaking out of probe replacment. Or interference.

Hope that helps

 

[Symbiot]

I wish it was so..

I started with the GHL profilux probe...
then moved on to an Elos laboratory grade probe
then a Mulwaukee probe..

all with the same issue...

 

[AQD_ottawa]

Then interference is hanging the probe, most likely the solenoid.

I had a similar issue, my lead ran right by the solenoid, when it kicked in the reading went scatty and sometimes used to freeze that was on a pinpoint controller some time ago.

If it was the profiLux you would get no reading at all or not calibrate as it does it rules out the PII, it also would be a first for a Profilux to have such an issue . I know it is easy to always blame the beast, but a forum search will show nothing even close to such an issue, thankfully profiLux rarely if at all gives issues, and nearly all are traced back and proven to be outside influences, all i am saying dont spend too much time worrying it is the main unit, look for the outside influences.

Seriously though check your cable runs, this sounds too much like interference.

The way to check this is to calibrate the probe and then leave in a jar away from the fish tank by some ways, and monitor the reading over a period of time you feel the issue should re represent itself and then email sales@ghl-profilux.co.uk for further assistance.

 

[AQD_ottawa]

Check also the placement of the probe in regards to the media, a blocked membrane will give the same issues on ANY probe.

Does not matter what probe you use if the probe is in a high density of dissolved solids the membrane will block quickly.