View Full Version : Problem with pH
Thomas111
04/05/2010, 05:41 PM
I've been seeing my pH dip into the low 7's lately and adding pH up (couple of different brands) made it go up but it came right back down in short time. I have an AC3. I tossed the pH probe from the freshwater tank into the SW tank and it read 8.3 on my AC3. I hooked up the SW pH probe to the AC junior and it now reads low sevens.
I came home today and found the pH reading 1.75 and the ORP reading 700. This is before I did all the stuff in the first paragraph. Like I said I hooked up the other probe from the FW tank and calibrated it but I'm still only at 7.28. I'm wondering if something could be wrong with the AC3 itself. Any thoughts? or ideas.
swearint
04/05/2010, 05:47 PM
After calibrating on the AC3, did you then measure the solution to see if it reads as expected?
Todd
aquamanic
04/05/2010, 06:02 PM
You might want to clean the probe also. Unplug it, soak in vinegar for a couple hours, then use an old very soft bristle toothbrush to clean the glass membrane, rinse with tap water. Then re-calibrate as Todd suggests and see if that doesn't clear things up a little.
Thomas111
04/05/2010, 06:26 PM
That's all OK. I went to the controller and started unplugging probes. ethernet, ect. I unplug the IO cable and the pH jumps right up to 8.10(lights are off). I plug in, back to 7. Unplug, back to 8.10?????????????????????
RussM
04/05/2010, 06:40 PM
By IO cable, do you mean for a breakout box, or the telephone-like cable to the DC8?
Thomas111
04/05/2010, 07:06 PM
The IO cable for the breakout box. I was just doing a little more investigating. I have two floats on there. One does the work and the 2nd is a safety. I thought that because the IO cable was apparently the problem maybe one of the floats is bad. I saw that the top of the safety float looked rusty.(it's a plastic float).
I disconnected the float and plugged the IO cable back in. PH stayed at 8.19. I added back a new float for the safety and pH still is ok at 8.19. I then unplugged and plugged the IO cable in several times and the pH is staying right where it should. I don't have a meter at home so I will check the float tomorrow at work.
Has anyone seen anything like this or explain what I experienced?
RussM
04/05/2010, 08:10 PM
You have, I believe, a case of saltwater somehow touching float switch wire... possibly a crack or nick in the insulation, or in the expoy or other sealant where the wires go into the float switch. That's what I suspected when I asked if it was the breakout box.... I helped friend diagnose similar behavior a while back, and that's exactly what it was - a new float switch cured the problem.
Thomas111
04/06/2010, 05:45 PM
That must be what happened. The epoxy where the wires feed in is gone. The float switch I checked this morning for continuity and it still works. Now one day later with the new float and the pH is as it should be.
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