PH reading fluctuating

[nickjj]

I am trying to isolate a problem with my ph reading. It fluctuates within a .10 or so reading every couple of seconds. If I disconnect the probe from the interface should the ph reading be stable? When I do disconnect the probe it still fluctuates. Is this a sign of a bad ph interface?

I should add that I tried the ph interface with a new pinpoint probe and get the same results. I am waiting a day or so for the new probe to acclimate before I try calibrating it. But for now it is still bouncing around.

Any ideas?

[Untamed12]

I don't have the answer...but you are not alone with the problem. I have two active pH interfaces. One of them gives bouncy readings, the other is very stable and it is like that through multiple probe replacements.

When I look at the system details, one of the probes has v6 firmware and the other has v7 firmware. However, AQT says that pH module firmware isn't upgradeable.

My question was a few spots down from yours on the AQT forum help.

http://www.aquatronica.com/forum/forum/problemi-hot-line/528268204

[nickjj]

It has been rock solid for years and then all of a sudden it's bouncing all over the place. Nothing changed equipment wise in my tank when it occurred so I can't see it being interference. Does your ph interface feel a little warm? My probe firmware is version 6.0 and hardware version is 2.

I still haven't gotten a reply yet on AQ Direct line for support in any event it is out of warranty and they probably couldn't do anything anyway.

[RobbyG]

Most likely you have stray voltage in your tank from some piece of equipment. Take the probe out and place it in a cup of the Tank water, if the reading stays constant then you know for sure that have stray voltage in your tank.

[catastrofe]

<a href=showthread.php?s=&postid=14820736#post14820736 target=_blank>Originally posted</a> by nickjj
It has been rock solid for years and then all of a sudden it's bouncing all over the place. Nothing changed equipment wise in my tank when it occurred so I can't see it being interference. Does your ph interface feel a little warm? My probe firmware is version 6.0 and hardware version is 2.

I still haven't gotten a reply yet on AQ Direct line for support in any event it is out of warranty and they probably couldn't do anything anyway.

I had the same issue. . .replaced the probe. No more fluctuation.

:D

[RobbyG]

Try isolating it first, what does it cost you to check!

[nickjj]

I bought a new Pinpoint PH probe just to make sure it was the probe and I get the same results. Even when I tried to calibrate the probe (after I let it sit in my sump for a couple of days) outside the tank in the calibration fluid the reading never settled. It kept fluctuating so I'm not even sure the probe is calibrated properly.

I swapped the usb to the other power bar and same results. Even if I disconnect the probe from the interface the reading still jumps around. It's got to be the interface which is about 3 years old.

[RobbyG]

At this point it sure seems like it.

[nickjj]

Well I filled out a support request on the AQ site and they replied very quickly. I'm pretty impressed with this new direct support so far.

[Untamed12]

I randomly stumbled across this thread and I will add my recent experience.

The pH reading from my Ca reactor was very jumpy...fluctuating within +/- .5 (not .05) every second. Having changed my pH probe a couple of times, and recalibrated many times...I decided to switch the pH module itself. This immediately solved the problem.

Most recently, the pH reading I'm getting from my tank sensor has begun to fluctuate also. Now, I'm immediately suspicious of that pH module as well.

[RobbyG]

Thanks for the info Untamed, and BTW nice to see you back here.

[nickjj]

Looking through the AQ forum i realized i never posted what the real problem was with the ph module on this thread. Being the "take it apart kind of guy" I noticed that the ph module bn connector for the probe was a little loose. Once I got the cover off the ph module the bn connector for the probe was lifting from the circuit board. A little dab of solder fixed up the unit back to normal.

I guess all the probe swapping over time the bn connecter broke the solder joint as you twist it off.

Anyways hope this explanation helps.