Topic: SMS 122 pH controller: can't calibrate low pH ??

[Sandalphon]

I am finally setting up an automated CO2 system. I calibrated the offset per the instructions for neutral pH with the 7.0 solution.
But I am unable to calibrate the slope using the 4.0 pH solution. I turned the slope adjustment screw on the back as far as it will go but I still get a reading of 4.7. Is this normal and does it matter?

thanks!

[Sandalphon]

Well I have been reading up on my pH controller. I think the electrode is too old and/or my calibration solutions are too old.

[Essabee]

I just don't have any experience of a Ph controller so I cannot help you with it.

If you have a couple days holiday you can adjust the flow of CO2 using the needle valve and bubble counter to a level that is safe and effective, you will not need the Ph controller then. I would like you have a drop-checker for fine tuning the CO2 on the higher side, but you could even do without it if you slowly increase the CO2 flow till you achieve the higher level by observing the fishes in your tank.

[Sandalphon]

I have another problem. When the CO2 shuts off, water sucks back into the co2 tubing. It sucks back really slowly, but if left for a few hours the water will go all the way to the bubble counter. The bubble counter has a check valve which seems to be holding so i dont know if this is normal, or if i have a leak or some other problem?

thanks!

[Essabee]

You have a leak. Check your CO2 line with soap water with the system on. Please see to it that none of the soap water finds it way into the aquarium - that would be disaster.