Re: pH monitors and temperature

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

> > > . . . Today's monitors and probes have a
> > > temperature sensor included in the probe and the
> > > correction is done automatically, which is why we don't
> > > need to worry about this factor.

Indeed, we don't have to be concerned about temperature, but that 's
because the differences are within the "margin of error" for
planted aquaria/tropical fish purposes.  


> > Wonder why the calibration fluids are marked for temperature.
 They
> > were made for old (type) probes?  They are old fluids? . . .
> 
> There is a distinction between temperature correction for the
> _probe_ and the variability of the pH of the _buffer_ solution
with
> temperature.

Purposes and truth are not always equally demanding.  One would need to
be concerned about temperature if one needed to be concerned with very
fine degrees of difference -- which aquarists, generally do not.  Temp
makes a diff, just not to us -- I don't know what high quality labs AM
is marketing those little packets to, though ;-) .

To sum up:  even if your probe compensates for temp, the calibration
fluid does not -- it's not 4.0, or 7.0 or 10.0 all the time --
sometimes you're actually calibrating to 4.1, 6.9, 9.86, etc.  But
planted tanks can't make use of that kind of precision anyway.  I doubt
that they can make use of "two-decimal places" reading either,
but the Pinpoint is nicely priced monitor that is durable and reliable,
and the second decimal is easily ignored (or one can get used to just
rounding).  I would guess that the accuracy of the meter is less than
two decimal places anyway -- which still makes me wonder why those
little home user packets are marked for temp.  Maybe labs do buy those
little packets or maybe it's just marketing to emphasize accuracy.

Scott H.

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