weird readings on my pH probe please help.

[madadi]

ive had an old aquacontroller for a long time. its a revesion 1.11 i never tried to use the ORP control function on it but today i tried to use it and every time i plug in the ORP probe my pH reading is going up and down. as soon as i unplug the ORP probe the pH reading goes back to normal. also without even using the ozone generator my aquarium water is reading around 90mV. im not sure thats normal or not. do i need to ground my tank water! or what needs to be done. i should mention that the ORP probe is old and hasnt been use for a long time. but its always been in its storage container with liquid inside. any help with be great. thanks in advance

[DaveJ]

I have the same problem with a second pH probe in the ORP slot. I would be interested in feedback from the neptune folks as well.

[RokleM]

I had the same issue. It's not listed in the documentation, but you have to calibrate the pH probe when it's used for the first time in the ORP slot. Mine was reading something crazy like 90-100 pH.

I don't know if you have to re-calibrate again if you switch from pH to ORP back to pH after it's been calibrated once.

[lvreefer]

Which controller do you have?
Also, for dual pH probes, you have to calibrate both probes together walking through all of the steps. So both of the probes will travel through each (7, 10) calibration solution twice; rinse your probes in clean water between solutions.

[madadi]

the controller is a neptune system aquacontroller v1.11 with a neptune pH and a pinpoint ORP probe. im going to try to calibrate the pH while the ORP probe is pluged in also. maybe that will make a diference. i calibrated it when the ORP probe was not pluged in. and now that i pluged both in, the reading is not constant till i unplug the ORP probe and only use the pH by itself. any advice would be cool. thanks in advance

[clp]

I think that the ORP probe has a leakage current problem, and needs to be replaced.

Curt

[madadi]

i think that could be the problem because its a very old probe. when i got the ORP probe it was used already for a while. i figured as long as its wet its probably still ok, but i guess not. im going to try to get a new probe and see if thats going to help. maybe i should also have the ORP plugged in while i calibrate the pH probe. im not sure if thats required, maybe someone should jump in about that and let me know if they use an aquacontroller both with pH and ORP together and if they had to be both plugged in while calibrating to be accurate.