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Re: pH 6.4, kH 7.0 What's going on?

On Mon, 9 Nov 1998, Carlos Munoz wrote:

> Do you use a pH buffer like "PH Down" or peat?  That will change the pH
> independent of CO2.  You can't use the pH/KH/CO2 charts if you have peat or
> a pH buffer other than the "natural" carbonate buffer.

This may seem like an unecessarily technical point, but these things don't
change pH independent of CO2.  They change the alkalinity.  The
quantitative relationship between pH, CO2 and *bicarbonate* is still
correct.  Unfortunately, if there are significant levels of other buffers
in the water then alkalinity doesn't measure bicarbonate, it measures
bicarbonate plus the levels of the other buffers.  In the presence of
other buffers the alkalinity will be a high estimate of the bicarbonate
content and the pH-CO2-KH relationship will always yield a high result for

Roger Miller