Aquatic Plant Central - View Single Post

MarcosB · 03-10-2006, 11:35 AM

Hoppycalif
There is no reason to a water sample in equilibrium with atmosphere has CO2 levels as far as 3 ppm. The equilibrium is related to CO2 levels in atmosphere, which is estimated at 380-390 ppm.
There are some possible situations where the CO2 can be far from the theoretical equilibrium of 0.5 ppm. This includes an ambient with poor external air ventilation, water with high biological activity (with microorganisms).
I do not understand how can you determine the CO2 equilibrium level with this experiment that you are developing.

Bert H
Compounds like phosphates and humic acids (and others) can interfere in the carbonate alkalinity determination. The KH value became higher than the real leading to errors when compared to pH x KH x CO2 charts.
But these compounds can also capable of influence this method based on pH. The pH variation due to the CO2 loss in a water sample that the KH is constituted only by bicarbonate/carbonate is higher than a water sample with the same KH value but with the buffering constituted of only phosphate salts.

03-10-2006, 11:35 AM	#36 (permalink)
MarcosB Junior Member Join Date: Oct 2005 Location: São Paulo - Brazil Posts: 4 iTrader Ratings: 0 Plant Points: 3600	Hoppycalif There is no reason to a water sample in equilibrium with atmosphere has CO2 levels as far as 3 ppm. The equilibrium is related to CO2 levels in atmosphere, which is estimated at 380-390 ppm. There are some possible situations where the CO2 can be far from the theoretical equilibrium of 0.5 ppm. This includes an ambient with poor external air ventilation, water with high biological activity (with microorganisms). I do not understand how can you determine the CO2 equilibrium level with this experiment that you are developing. Bert H Compounds like phosphates and humic acids (and others) can interfere in the carbonate alkalinity determination. The KH value became higher than the real leading to errors when compared to pH x KH x CO2 charts. But these compounds can also capable of influence this method based on pH. The pH variation due to the CO2 loss in a water sample that the KH is constituted only by bicarbonate/carbonate is higher than a water sample with the same KH value but with the buffering constituted of only phosphate salts.