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Re: pH control

> From: "Dixon, Steven" <stdixon at bechtel_com>
> Subject: pH on the Rise
> Increasing your carbonate hardness (KH) will reduce pH swings associated
> with variation in the CO2 supply.  If your KH is 2 or more, your
> probably okay.

	If the KH is anything other than _very_ low, then KH has no
effect on the size of the pH swing resulting from a given CO2 concentration
change (ratio change, not difference).  Check the table and see.  What
the KH _does_ change is the absolute pH for a given CO2 concentration,
and that increases by 0.3 for every doubling of KH.

	As Steven says, if the KH is 2, you have no problem, and you 
can probably use less.  What a large KH _does_ protect against is the
effect of adding strong acids.  If HNO3 is generated in your tank,
then it will use up the KH, and when it runs out......

Paul Sears        Ottawa, Canada