i dont think my pH probe for my pH controller is functioning

[Atl300zx]

i am 99% sure my pH probe for my pH controller isnt functioning. I turned off the Co2 for now just to be safe. According to the pH controller, the pH would never get below 7.0 even after running CO2 for 5+ hrs at about 5-6 bubbles/sec. It was at 7.0 for over 3 hrs. I did a pH test with liquids and it was between 6.0 and 6.4 (leaning more towards the 6.0 side).

What should I do?

 

[rkilling1]

I would perform a pH measurement of the calibration solution (7.0) with the liquid test kit and see what it reads. This would see if the pH kit is correct.

I assume you are calibrating with pH 4 and 7 solutions? I would place the pH probe in both of those and see what it is reading.

I just read through your earlier posts and see that you don't have a calibration solution. I would not trust that probe until you get new solutions in and recalibrate it. Once it is calibrated with known buffers, you can trust that probe more then that liquid test kit.

 

[Atl300zx]

I calibrated it originally with just ph 7 solution. That is all the came with the probe and the vendor i purchased it from said that was fine.

The pH probe when received had the protective cap on it and the crystals. I rinsed them off and then calibrated it in the pH 7 solution. Unfortunately i dont have that solution anymore to test iwth my kit. This morning after turning off the CO2 flow last night, the pH meter read 8.1 while my test kit came back a perfect 7.0

I contacted the original vendor that sold me the pH controller and asked for some replacement calibration solution and some reactivation solution in case my probe did dry out.

Hopefully i can get this sorted out before i lose any more fish. For the time being i put the CO2 on a slow bubble rate ~ 1/sec. Will this allow the pH to get to low?

 

[Devilishturtles]

Sounds like a good idea. Most pH probes come with a 4.0, 7.0, and sometimes a 10.0 solution to calibrate with, like rkilling1 said. It's all important to make sure the probe is working correctly.

Hope you get things sorted out with the new parts.

 

[Mr.pH]

I calibrated it originally with just ph 7 solution.

That's not enough, you need two point calibration with two solutions. Although in most cases if the meter is working correctly calibrating it for 7.00 will give reasonably correct readings in the 6-8 range. Thing is, one point calibration doesn't give information whether the pH meter and pH electrode are working correctly.

asked for (...) some reactivation solution in case my probe did dry out.

That's not an easy task and I doubt you will be sold anything helpfull. You may try to simply soak it for 24h in the pH 7.0 calibration buffer. It may help, for sure it won't make things worse. Next stages are described here:

http://www.ph-meter.info/pH-electrode-rejuvenating

Note that gelled electrodes will probably not survive heating.