Help with ph controller....

[Lonewolfblue]

It's time for cleaning, and I soaked the probe in the cleaning solution, then went to the 7.0 solution. Read 7.3, so I recalibrated it to 7.0. Then I went to the distilled white vinegar, and it was almost 4.0. Then, when I tried adjusting the slope, it would only go down to 3.4. Wouldn't turn any more. Is my probe bad? Or could I be doing something wrong? How often do the probes need to be replaced? I've only had this one since March.

 

[Lonewolfblue]

bump...

Still not working correctly...

 

[Lepomis]

Probe shouldn't be bad. I would wonder more about the quality of the buffers. Might want to invest in some additional buffers and try again, if still no luck sounds like time to return to sender if an option.

 

[Lonewolfblue]

I could try new buffers, but here's the thing. The distilled vinegar I used was a brand new bottle, unopened. Also, when I calibrate to 7.0, and place the probe in the tank, it reads 6.4. Then I use the AP test kit, and the color is roughly 6.4, maybe 6.5 at the most. So I know it's correct at the tank. It's just that I can't calibrate the slope for some reason.