Re: [APD] GH vs. PPM

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

For those of us that didn't take organic chemistry because
we thought it was about clocks that dripped over the edge
of tables, how do the organic acids come into play?

sh


--- Roger Miller <roger at spinn_net> wrote:

> Liz wrote:
> 
> > If the pH is X and the KH is Y then the CO2
> concentration is always Z
> > regardless of other acids present if you have a steady
> state that
> > looks like an equilibrium.
> 
> This could be true, depending on your definitions.  It
> would be more accurate 
> to rephrase this to say:  "If the pH is X and the
> bicarbonate concentration 
> is Y then the CO2 concentration is always Z regardless of
> other acids present 
> if you have a steady state that looks like an
> equilibrium."
> 
> The problem is that some "other acids" can be measured as
> part of the KH.  KH 
> is then an inaccurate representation of the bicarbonate
> concentration.  Mono- 
> and dihydrogen phosphates can have that effect but they
> -- without large 
> intentional additions -- rarely reach concentrations high
> enough to be 
> significant.  Probably the most common interference comes
> from organic acids 
> that originate from wood and peat.

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