Re: [Killietalk] pH (was Re: copper leaching from new plumbing)

[Wright Huntley <whuntley at verizon_net>]

LeeH920226 at aol_com wrote:
> All the discussion of pH overlooks the fact that, unless you calibrate any pH 
> meter every time you use it the readings are worthless. Litmus paper or pH 
> paper is more likely to be correct, even though not precise.
>
> Lee Harper
> Media, PA
>
>   
You might just have a very poor or damaged meter, Lee.

1. I don't expect 0.01 point accuracy, and

2. my meters don't drift much at all if I am careful about storing the 
sensors wet and tightly sealed.

With proper calibration fluids to do a two or three-point check, once in 
a while, my meters have far, far better resolution than any 
color-comparison test. Accuracy (absolute) is at least as good and 
probably quite a bit better, if my calibrating buffers are any good.

I admit, if I haven't used a pH meter for a few months, I cannot resist 
giving it at least a one-point check. Mine are rarely very far off, tho, 
if storage was proper.

If you store the electrode in the wrong stuff, or let it dry out, all 
bets are off. It may be squirrelly from then on.

BTW, I use the 4.0 buffer test solution (mild acid) and a brush to clean 
off any scale that may develop on a probe tip over time. I also try to 
not store it wetted with hard alkaline water which could leave 
hard-water precipitates on (and in) the porous glass. My pH probes seem 
to have "infinite" life (unless I break one).

All this fuss is a good reason I hardly ever use them. Only if pH is a 
definitive factor (and it very rarely is) will I go to this much bother.

HTH

Wright

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