"Ken Anderson" wrote in message
...
I am trying to figure out why I got 3 different readings in a
row. Tomato sauce, actually. I calibrated, tested. Recalibrated,
tested.
Recalibrated, tested. Even if my pH 4 and pH 7 fluids were old, I'd
expect
repeatability. Two place resolution, +/- .04 accuracy. I got 4.41, 4.16,
and
4.30.

Personally, I'm from the "stir gently, wait, stir again and wait until the
reading stabilizes" school. I do this when running standards too. It takes
time for the reading to settle to a final value. Also, the time required to
stabilize will lengthen with age of the probe. Supposedly, contact lens
enzyme cleaner helps restore/clean dirty probes.

BTW, I had trouble with flaky connections between the probe and body of my
Hanna Piccolo, so I soldered jumper wires between the sets of contacts.
That did the trick.

Tom S