Calibrating PH Probe

[Big Country]

I've always wondered how long to wait when calibrating a PH probe.  The instructions say to let it settle, when is that?  My ACIII readout just says settling, have never seen it say settled.  I've let it sit in the calibration solution for 15 minutes in the past, tried something different last night and watched the numbers, when they stopped moving I hit select and moved on.  When the probe calibrated it told me my PH was 8.45, never seen it that high so I doubt that the probe is correctly calibrated.

[Brian Ward]

I assume you're using the 7 and 10 solutions to calibrate with? Assuming this is true, I usually just do as you said and let it run until the numbers don't move for about 1-2 minutes and lock it in. You should initially confirm your readings with a chemical test you trust.

[Big Country]

Yes, I am using 7 and 10.  I was in a hurry yesterday.  Normally I watch the numbers and when it settles on a number for a whole minute I consider that good.  I just tried to speed up the process yesterday by telling myself that when the numbers settled for a few seconds that it was good.  Like everything else in this hobby, nothing good happens quickly.  Will recalibrate this evening and see if I get something more logical, will see if I have a PH test kit handy to check against.

[howaboutme]

Probes only last a year or so.... You should replace regularly if you want accuracy. Perhaps it's age?

 

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[Big Country]

Well, got home this evening and PH read 8.69.  Disconnected older probe and connected probe I just removed from CaRx.  Calibrated it the way that I always had watching the numbers until it settled on a number for more than a minute.  Problem solved, started reading 8.11 which is close to what I expected by test kit.  Capped the old probe and put it in the cabinet for an emergency spare.