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Re: Adjusting pH

> From: Jerry Baker <jerrybaker at weirdness_com>
> Subject: Re: Adjusting pH
> Do KH test kits measure "effective" KH, or "real" KH?. I mean, when you
> add buffers you are changing the effective KH, but not the actual KH.

	When you add buffer systems other than bicarbonate/CO2 you _do_
change the "real" KH (bicarbonate concentration).

	For example:

	H2PO4-  +  HCO3-   <->   CO2  +  H2O  +  HPO4--

	It's an equilibrium, and if you know what you put in it is possible
to calculate where you will end up.  A KH titration will now show HCO3- and
HPO4--, but not H2PO4-.  It will be difficult to tell what is going on by
simple test kit measurements.  Don't try to use more than one buffer
system at a time - in our case CO2/HCO3-.

> Do
> the test kits pick this up? And if they do, does the chart still hold?

	The chart holds, but you can't measure KH, or the CO2 concentration
either, by any simple test kit method.

Paul Sears        Ottawa, Canada