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Re: CO2 & KH

> Tom wrote:
>> Nope. Often folks with Discus tend to add very soft water with low KH.
> Ok, except for the case of zero KH, when adding CO2, won't the shift be
> the same for high versus low KH?   Using that famous (infamous?) CO2 chart, it
> says that the shift will be the same:
> With a low KH (1.5 degrees), and a low CO2 level of 4.5ppm, the pH would be
> 7.0.  
> Now increase Co2 to 28ppm and the pH drops to 6.2, so the shift was .8
> Now with a high KH (15 degrees), a low CO2 level of 4.5ppm, giving a pH of
> 8.0.
> Now increase CO2 to 28ppm, and the pH drops to 7.2, resulting in the same .8
> shift.
> Yes? No?
Try it and see. See if you need **more** CO2 added(bubble in same amount to
each tank) to get that drop of .8 pH units. What cha get? Do you think
you'll use more CO2 for the 15KH tank or the same for that drop of .8 to
equal that of the 1.5KH tank? You tell me:)
Tom Barr