pH/KH/CO2 relationship in Amano's book

[PeterGwee]

The following article was extracted from APD site which also strikes interest to me as that was no reply to it in APD...how about experts here willing to voice their opinion other than DEA...hehehehe..you say is other form of buffers in amano's tank water..

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

[loupgarou]

ph/kh relationship applies only if without co2 injection, your water is ph 7.0 .

once you start usign ADA amazonia, nisso volcanic soil, blackwater, ketapang, that throws out the entire ph/kh chart.

I'm not certain if its just a simple offset in ph though.

[PeterGwee]

Since much phosphate accumlation will appear in planted or non-planted tanks which will in turn act as a non-carbonate buffer.This level will be high enough at a certain time and throw the ph/kh/CO2 relationship out of whack?

[DEA]

i believe so
other things like *cough* geoliquid *cough*, blackwater could conceivably alter the pH/kH relationship