Re: [APD] CO2 problems (??)

["Joel Fizette" <sentientpuppet at gmail_com>]

Has anyone made that into a calculator? because my tiny little brain doesn't
seem to wan't to wrap around that every time I want to know my co2 level...
If no one has done so maybe I will write it myself.

On 3/2/06, S. Hieber <shieber at yahoo_com> wrote:
>
> There might be some rickety tables out there ;-)
>
> There have been a number of formulas offered over the years that compute
> roughly the same CO2 values under roughly the same parameters, even though
> the formulas contain some very diff constants.
>
> I like the formula that was handed down after all the great discussion by
> Paul Sears, and George Booth and Roger Miller, and Jeff Ludwig, etc.. This
> version is actually adjusted for a temperature of about 78-80 degrees F:
>
> CO2 (in ppm) = 15.7*KH*10^(pKa(CO2/HCO3- system) - pH)
>
> generally                   =15.696*KH*10^(pKa-pH)
> @ 78-80F                  =15.596*KH*10^(6.34-pH)
> @ KH 9, pH 7            =15.596*9*10^(6.34-7.0)
>                                 =30.9 ppm
>
> KH 9, pH 7.0 => about 31 ppm
>
> I like this version because it directly incorporates the values for KH,
> pKa of CO2 carbonate relationship, and pH, with only one assumed constant.
>
> The value for pKa changes with temperature although the changes are very
> small. For example, at 70 degrees, pH7.0 and KH 9, the CO2 would be about
> 33 ppm. Of course the diff between 31 and 33 is less than the compound
> margin of error in doing home KH and pH measurements. ;-)
>
> If I've put things badly, there was a nice summing up of the points by
> Paul in this post:
>
> http://fins.actwin.com/aquatic-plants/month.200207/msg00186.html
>
> sh
>
> * * * * * * * * * * *
> The Northeast Council of Aquarium Societies (NEC) celebrates its 50th year
> of service at its 31st annual convention, April 7-9, 2006 -- including *An
> Evening with Aquarium Legends*.
>
> Read the speaker list, then download the registration form, and get set to
> join the fun at what promises to be the year's biggest tropical fish
> convention.
>
> http://northeastcouncil.org/html/
>
> And while you're there, attend the AGA's annual meeting Friday afternoon
> (2-4pm). This year's speaker is Claus Christensen, Tropica's Managing
> Director.
>
>
> ----- Original Message ----
> From: Billionzz at aol_com
> To: aquatic-plants at actwin_com
> Sent: Thursday, March 2, 2006 1:05:16 AM
> Subject: Re: [APD] CO2 problems (??)
>
>
> >>>By the way, correct me if I am wrong but KH 9 and pH 7.0 yields  about
> 27
> ppm of CO2.  Not 170.
>
> I use the formula:  3*KH*(10^7-pH)
>
> That means 3*9*(10^0) = 3*9*1 = 27 ppm.
>
> Or am I  missing something?<<<
>
>
> With a KH of 9 and a pH of 7 the CO2 would be 27.
>
> Here is the formula    3*KH*10^(7-pH)
>
>
> Bill
>
>
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