Re: pH meters

["S. Hieber" <shieber at yahoo_com>]

Hopkins, Samuel asked:

>      Can someone recommend a PH tester around $100US?
> Sharp meters are cheap
> but have an accuracy of +/-.2!!
> 

Pinpoints have a good rep, cost about $90, and are pretty
accurate if you keep them calibrated (about once oa month
jsut to be safe).  

At the risk of sounding like a smart ass, and I don't mean
to be one, don't confuse display resolution with accuracy. 
The display might resolve down to 0.01 degrees but the
instrument, all things considered (technique, calibration,
etc.), might only be accurate to 0.05 or 0.1 or something
like that.  Usually, at a minimum, I think you need to
allow that the accuracy is at least half of whatever the
digital meter resolution is -- consider, is the true value
just under or just over a threshold for the display to
change.

Scott H.

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