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Re: KH=1

> Date: Mon, 24 Dec 2001 13:40:01 EST
> From: Paulio629 at aol_com

> If Im not wrong, raising the kh will in turn raise the pH. Am I right about 
> this?

Not exactly, but yes. ;-) [Remember free advice is worth every penny! <VBG>]

It would only change if a weak acid (like injected CO2, forming carbonic acid)
was pushing the pH below the natural buffered pH level. Buffers, like KH, try
to hold pH very constant, until something overcomes them. The salt,
(carbonate/bicarbonate) holds pH in the high 7s or low 8s (I forget the actual
value), unless there is enough of the acid of that salt (carbonic) to lower
the pH.

It is an equilibrium balance, with pH telling you the ratio of the salt/acid,
effectively. If you know how much salt (KH), the charts show how much acid
(CO2). pH is just the indicator.

That's why the KH-CO2 chart is such a great tool for measuring CO2
concentration, in the absence of other acids or buffers. Higher KH tends to
"buffer the pH high." It thus takes more CO2 to lower the pH by the same
amount. The pH has thus become more "stable."

If you already have significant CO2 dissolved, then raising the lowered pH by
increasing KH is quite likely, especially when you start down around KH=1
(much too little buffering for good stability, IMHO).


Wright Huntley -- 650 856-4245 -- 879 Clara Dr. Palo Alto CA 94303

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