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pH/KH/CO2 relationship in Amano's book
I finally bought a copy of "Nature Aquarium World" by Amano. It is a
beautiful book, but I don't understand some of the data he gives for his
tanks. I normally calculate CO2 levels (mg/l) from pH and kH
measurements, using a table that George Booth incorporated into an article
he wrote based on the Dupla 10 Golden Rules. The CO2 concentrations that
I obtained from this table when I used the pH and kH data in Amano's book
do not come close to the CO2 values that Amano gives. For example:
Tank # kH pH CO2 (mg/l) CO2 (mg/l)
Amano's data George's table
29 1 6.8 16 5
44 1 6.8 23 5
41 1 7 19 3
1 2 6.8 16 9
7 2 7 16 6
43 2 7 23 6
28 3 6.8 17 14
31 3 7 13 9
22 3 7 19 9
It seems pretty clear that Amano consistently gets higher CO2 levels than
I would expect from George's table. Also, Amano's CO2 levels seem to be
almost independent of kH/pH: for example tanks 22 and 41 both have pH=7
and CO2=19, but have kH 3 and 1, respectively.
I believe that George's table is reliable, so does anyone have any ideas
why Amano's values disagree so strikingly with the table? Are CO2
concentrations difficult to measure?
Roger Crowther