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Re: pH meter calibration

To: Aquatic-Plants at actwin_com
Subject: Re: pH meter calibration
From: Wright Huntley <huntley1 at home_com>
Date: Tue, 20 Apr 1999 13:10:39 -0700
References: <199904201948.PAA06958 at acme_actwin.com>


> Can you use distilled water to calibrate a pH meter at 7?
> 
> Thanks
> Sherlock Wong

Sorry, Sherlock.

Not a chance. Distilled water does not have a pH of 7 (atmospheric CO2
drives it lower) and it has no buffering. [Measuring distilled, DI or
even RO water pH is generally not worth the bother, as results can vary
wildly, BTW.]

You need a solution that has been accurately buffered to pH=7, or the
tiniest contamination from your probe will make the pH read almost
anything.

Frequent calibration checks *are* a vital process, particularly with the
inexpensive probes we use, and our aquatic environment. Buy buffered
solutions, tho.

Wright

-- 
Wright Huntley, Fremont CA, USA, 510 494-8679  huntleyone at home dot
com

                      Stop passing new laws!
       Repeal some dysfunctional ones. It will do far more good.* 
             http://www.self-gov.org/libertarianism.html
________________________________________________
*The 9000+ pages in the IRS code is a neat place to start trimming.

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