Ph probe

[Xxflounderxx]

On my neptune EL I have a pm1 module and my ph probe is reading low so I tried to calibrate it but it would read the 10 solution after calibration it would read 9.0 I tried 2 more new ph probes same result any ideas?

 

[n2585722]

If it is a new probe you may want to wait a few days and recalibrate. The new probes are stored in a storage solution that is near a pH of 4 so once they are out f that solution and in tank water they will tend to drift for a few days. I am not familiar with the Apex calibration but most have 2 or 3 calibration points. The first one you need to do is the offset calibration. the other one or two are gain calibration points. Since order makes a difference use the recommended procedure. I usually let t sit in each calibration fluid for about 5 minutes or until it quits drifting. After calibration ai go back and check the first point and if it is off I go through the calibration again. Sometimes it takes more than once to get it in since any change of 1 point will have an affect on the others and they may need to be done again depending how much change is made. Hope this helps.

 

[Xxflounderxx]

I have let the probe in the tank for two days then tried to recalibrate it is still off exactly by 1.00 no matter what I do

 

[n2585722]

If you have tried more than 1 pH probe and get the same results it sounds like an issue with the controller but it could be some setting that is off. Unfortunately I do not have any experience with Apex so hopefully someone will post that does. #apexusers