# Re: ReCalculate CO2 -- or - putting all the CO2 cards on the table(s)

• To: Aquatic-Plants at actwin_com
• Subject: Re: ReCalculate CO2 -- or - putting all the CO2 cards on the table(s)
• From: "S. Hieber" <shieber at yahoo_com>
• Date: Tue, 2 Jul 2002 03:41:04 -0700 (PDT)

```Roger Miller commented on the formula that is/should be used in the
CO2-KH-pH table, saying in part:

>> >>    CO2 = 12.839 *KH * 10^(6.37-pH)

CO2 ppm = 3.6*KH*10^(7-pH)

>Some people (including myself) disagree with the unit
> conversions that lead to the value of 12.839 in the first formula
> above.  The
> value of 3 in the second formula is based on the same unit
> conversion.
> There's fairly extensive discussion of the difference in the
> archives, but it
> really isn't easy to find.  For the alternate versions replace the
> first of
> these formulae with
>
> CO2 = 15.664*KH*10^(6.37-pH)
>
> and the second with
>
> CO2 = 3.6*KH*10^(7-pH)
>
> The KH-pH-CO2 charts and tables have never been changed to reflect
> this
> difference because (1) when you consider all the other possible
> problems with
> the method the change would be a fairly insignificant improvement (2)
> because
> George has never agreed and (3) because noone has bothered to do the
> work to
> recalculate everything.

making new tables is easy enough.  I have all four in Excel if anyone
wants them.  I'll forward to Erik in case he can find the time and
reason to use them.

These tables extend the ranges beyond what's likely.  delete columns or
rows as you see fit.

Scott H.

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