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pH/ KH tables

Hi all,
it states that atmospheric CO2 is only 3 ppm. Was surprised by this as other sources I dictate more like 400 ppm
Yes <"it is 415 ppm and still rising rapidly ">.
co2-chart-increase-mauna-loa-1960-2019.png

The 3 ppm figure is the datum level of dissolved CO2 that the dKH/CO2/pH was based on. The theoretical value is less than 1 ppm CO2 (<"based on Henry's law and the solubility of CO2 at 20oC">) so there has been much debate as to where the 3ppm figure came from.

Have a look at <"Determination of CO2...."> (and linked threads), it has a much more complete discussion.

cheers Darrel
 
Thanks for that Darrel. I understand now. Whilst atmospheric concentration is about 400ppm, the maximum dissolved in water, at equilibrium, is 3ppm.
 
Hi @hypnogogia

I can see where the confusion arises. Dennis Wong's site states "...as a tank without CO2 injection will always be near atmosphere equilibrium (where CO2 <3ppm or so)". This would benefit from rewording.

The 2HR Aquarist is an excellent resource. And, I've just noticed that it is now possible to send an email to this company. The previous feedback system didn't work very well so this should be a worthwhile improvement.

JPC
 
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