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Re: CO2, KH ....yet again.

> From: Michael Moncur <mgm at starlingtech_com>
> Subject: Re: Seachem Flourish and KH question
>  >CO2 injection causes the formation of carbonic acid (H2CO3).  Because
>  >alkalinity is primarily a measure of CO3, the CO2 injection will stimulate a
>  >lowering of pH no matter what the kH is.  The pH will still go down.
> I'm sure this is true in theory, but doesn't a higher KH make the pH change 
> due to CO2 smaller?

	NO.  This has come up many times.  The _change_ in pH, for a given
change in CO2 concentration, is the same whatever the KH. The actual pH will
be higher for a higher KH.

	Double the CO2 concentration, reduce pH by 0.3 (log(2)).
	Double the KH, increase pH by 0.3.

	Look at the archives or the KH/pH/CO2 tables.

Paul Sears        Ottawa, Canada