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Re: pH Meters and Electrodes (long, as usual)

> Date: Wed, 16 Aug 2000 14:47:12 -0500
> From: Lobos <lobos0331 at yahoo_com>

> George - I keep mine in a saturated KCl solution between uses.  I have
> had mine for a year and it still measures pH 6.3 water accurately.  Are
> your pH calibration solutions old?  This can be a problem when
> calibrating the electrodes.  

Yes they are. I'll tell Karla to get some new stuff. 

It *seems* like the pH 7.0 solution cals the probe OK. Do you know the specifics 
of the problem? Does an older solution make the electrode go wacko? Or is it 
just an incorrect pH reading?
> My pH pen has an automatic temperature
> compensation and automatic calibration when calibrating the electrode.
> Do your pH meters have automatic temperature compensation?

AFAIK, no. That takes a special electrode. I suspect the pens have a 
thermocouple near the electrode for this?  Since the aquarium water stays at a 
constant temp and we make sure the cal solution is at the same temp, I'm not 
worried about temperature effects. 

George Booth in Ft. Collins, Colorado (booth at frii_com)