PH Reading out of wack

[revnull]

Every few months or so my PH reading spikes causing me to freakout. I run to my tank to make sure my kalk pump has not dumped a white cloud of death into my tank. Sure enough, everything is fine and the fish are happily swimming about. I recalibrate my PH probe with the required solutions and the readings are fine for another couple of months. If I were a betting man, I would say the controller is loosing it's PH calibration every once an a while. I understand that we are supposed to recalibrate our probes every once and a while, but the spikes that I'm seeing are not the drift that you would see with probe falling out of the expected range.

Does anyone have any thoughts or experience with this problem?

BTW, I'm running 4.05_4B11

Thanks!

 

[Deleted member 143833]

There is a point in time if the probe is not cleaned and maintained that the sufficient dirt can build up on the probe to cause readings to wonder. If as you mention this happens every few months then I suspect that a scheduled cleaning and calibration slightly more often may solve your problem.

 

[revnull]

Granted, I do not fully understanding the mechanics of the PH probe, but wouldn't it stand to reason that if it were a cleaning issue there would be gradual drift as the probe went from clean to dirty. My PH readings go from predictable to haywire without warning.

 

[Deleted member 143833]

Not really; there is an interface exposed to the water and there may be a critical point where the reading drift a little or maybe only that the probe responds slowly to changes in readings but at some point the scale tips and then, like turning a switch it all goes south. By your description I still think this is your case. If you think otherwize you can read the calibration and slope value and see if they change over time but my bet is still the other.

 

[revnull]

OK, taking more of a diagnostic approach to my problem I cleaned my probe and placed it back in the water. The value dropped to 7.x while cleaning with RO water. When placed back in the tank, it returned back from 8.7x to low 9.x. It looks like cleaning in not the cause of my drift.

Looking at the current calibration values, I have -104 offset and 1.01b scale. Next, I'm going to recalibrate and report back my calibration values. In a few months when this happens again, I'll come back and update this thread with the new values to see if they "reset".

 

[revnull]

Wow, I think I have a bum pH probe. Even after calibration, my values are out of whack. Last night I mixed a bucket of fresh salt water, let it mix, heat and aerate over night. I tossed my probe in this morning and my readings still in the 9's. I would really like a better way of testing the probe before dishing out the green for another probe.

 

[BigKahuna]

Not to highjack the thread but my pH has crept up as of late and wonder if it's the probe too, which is about a year old. What is the life expectancy on these probes in general? I took it out and cleaned the probe gently and noticed the air bubble inside the probe that surrounds the wire goes almost half the length of the body. Is that normal? I don't remember seeing so much air inside there before to be honest.

 

[revnull]

I moved my probe to the other PH2/ORP port and tried to calibrate it, just to see if it was the Apex port. The value is still off. I too am interested in the average life span of the probes. Dose the "Lab Grade" last longer than the standard?

 

[CeeGee]

probes should be replaced at least once a year as I understand it. I have always followed this rule and never had a problem.

That said my less than 2 week old Apex is giving me abnormal pH readings. Going to call and see about having it repaired I guess.

 

[BigKahuna]

My Ph creep was just that it seems. I bought some calibration fluids and re-calibrated my probe and all is well. It was reading 8.65 by the end of the photoperiod for the main tank which I felt was probably the probe. After calibration at 4 and 10, which both showed to be around 0.4 high relative, it is showing a reading of 8.25 at the end of the day. My probe is about 16 months old. I don't know about changing them out every year if they still work and can be calibrated. I would just invest in a couple bottles of calibration fluids to check on it every 3-4 months and when they can't be calibrated anymore get a new one at that point. Also from what I've read it seems it is better to just have the probe body down in the water and not submerge the wired cap. Even though they are supposed to be sealed I don't think the harsh salt water environment is good for the rubberized cap and likely to harden it and cause a failure.

 

[CeeGee]

I am going to try and recalibrate and reposition the wire so I don't get "electrical interference".

Contacted Curt and he said he doesn't believe it is the Apex. He believes it is "electrical interference". I don't believe that though as it is hooked up and ran the same way it was on my AC Jr which never experienced this problem.

Seems these units have quite a bit of problems from what I gather which is a bummer. After all the money I have spent on neptune units I could have been sitting in a profilux unit which from what I can tell have no equal if you can afford them.

Hoping to get this resolved as I was told I could reach Curt before 5pm but when I called I got the answering machine.