Milan
Aquarium Advice Regular
I'm trying to figure out the way the CO2 calculation works, and I have my serious doubts about it.
Here is the formula:
CO2=3*KH*10^(7.0-pH)
There is also a table based on this. It appears to me it has an empirical background, but that's OK. What bothers me is that it's based on a single point pH/KH measurements, which in my mind is fundamentally wrong. Let me illustrate this:
Case 1:
Tap water is KH=6, pH=7.5
After X amount of CO2 dissolved, KH remains 6, but pH drops to 6.8.
Case 2:
Tap water is KH=6, pH=8.0
After X amount of CO2 dissolved KH remains 6, but pH drops to 6.8.
Case 3:
Tap water is mixed with RO and the final readings are KH=6, pH=6.8
No CO2 used (X=none)
Is the X in all 3 cases the same? I doubt it. But the above formula suggests
they are (CO2=29ppm). In Case 3, it's even absurd. This really blows my mind.
I my mind, CO2 concentration calculations should reflect the work (X amount
injected) needed to move the pH from point A to point B for a given KH. So,
two points, start and end pH! Could it be that in the above formula part in
brackets "(7.0-pH)" considers 7.0 (neutral) being a start point?
Chemistry not being my field, I may be seriously missing something here, but
if someone could comment on this, I would appreciate.
Thanks
Here is the formula:
CO2=3*KH*10^(7.0-pH)
There is also a table based on this. It appears to me it has an empirical background, but that's OK. What bothers me is that it's based on a single point pH/KH measurements, which in my mind is fundamentally wrong. Let me illustrate this:
Case 1:
Tap water is KH=6, pH=7.5
After X amount of CO2 dissolved, KH remains 6, but pH drops to 6.8.
Case 2:
Tap water is KH=6, pH=8.0
After X amount of CO2 dissolved KH remains 6, but pH drops to 6.8.
Case 3:
Tap water is mixed with RO and the final readings are KH=6, pH=6.8
No CO2 used (X=none)
Is the X in all 3 cases the same? I doubt it. But the above formula suggests
they are (CO2=29ppm). In Case 3, it's even absurd. This really blows my mind.
I my mind, CO2 concentration calculations should reflect the work (X amount
injected) needed to move the pH from point A to point B for a given KH. So,
two points, start and end pH! Could it be that in the above formula part in
brackets "(7.0-pH)" considers 7.0 (neutral) being a start point?
Chemistry not being my field, I may be seriously missing something here, but
if someone could comment on this, I would appreciate.
Thanks