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Re: pH monitor

Just a quick follow-up:  I'm still waiting for my calibration solutions
to arrive, but concerning the jumping values I was seeing, I received a
private reply form Andrew Bolling concerning a method to "rejuvenate"
an old pH probe. 

As I said, my probe seemed to be generally tracking the pH changes in my
sump when I did a water change, but the reading values would just over
a .3 pH range constantly.   6.61, 6.73, 6.69, 6.83, 6.75, 6,91 etc, etc,
etc.     Well, I followed Andrews advice, which was to soak the probe in an
acid, then to soak it in saturated KCl solution.   After doing that, I 
dropped the probe into my sump.   The pH slowly climbed until it reached
6.64, and it's sitting there exactly, no swinging around.     I moved the
probe to another tank (without CO2 injection), and it settled quickly at

So, thanks to all those who helped me out, especially to Andrew who
might have saved me the cost of a new probe.   I'll report how it goes when 
I receive the calibration solution.   And it's not on a pH controller, so it's
no big deal if it fails in the future.   So in addition to the regular 
calibration, I'll plan on doing the acid and KCL soak every 6 months or so,
and see how long the probe will last.  

Chuck Gadd