ADA's real CO2 levels

[Tom Barr]

Every so often I get someone claiming they only need to add 10-15ppm of CO2.
They claim high light(but do not measure it) and use a drop checker(hardly accurate based CO2 measuring).

Here's some old data:
http://fins.actwin.com/aquatic-plant.../msg00114.html

It is important to note, that the pH/KH table will often over estimate, but NEVER underestimate CO2.

So where is Amano getting such data? I know of no test that will produce such numbers measuring CO2.
CO2 measurement issues: the pH/KH table or less perhaps since KH may have some non carbonate alkalinity.
At such low KH's, there's little room for error since there's little potential for the KH to have non carbonate effects/contributions to the alkalinity.
Even if this was the case, the CO2 values would be LESS, not higher is ALL CASES. Peat etc, tannins, these depress the pH, but do not add CO2.
Thus they also falsify and make aquarist think they have more CO2 than they really do based on the pH/KH chart.

These measurements cannot be possibly correct. Testing errors/data manipulation must have occurred.

I am trying to think of any cases, where, the CO2 would be higher than the pH/KH chart would state.
I cannot think of any cases.

I can think however, of many user errors, temptations to say what is dogma, prevailing consensus, myths of what is best.
I could see the issue if the data had changed and they got better, the pH's dropped and KH stayed the same over the last decade or two, but, they have not.
So if anyone can tell me how they measure those CO2 ranges and check them against a known CO2 standard, I'm all ears.

[Matt F.]

I'd like to see more on this topic.

[Yo-han]

I am trying to think of any cases, where, the CO2 would be higher than the pH/KH chart would state.
I cannot think of any cases.

What if there are bases in the water, maybe a lot of ammonia:P

[Tom Barr]

The NH4+ is not enough to account for the differences. Most of the NH4 is not in the base NH3 form anyway at those pH's. And we would expect little to no residual NH4 in the water column for measurement of CO2 on a fully developed aged mature planted tank, it would be rather outrageous to post CO2 data based on the 1st week or so of set up, then show a pretty mature tank 6 months later.