I use DIY Co2 in my tanks. I disagree with this statement:
“Also, we add too much sugar.
Ethanol and sugar are increasingly toxic to yeast at greater than 10% concentrations.
Therefore 2cups (~500ml) of sugar in 2L of water (~25% sugar) is unhealthy for the yeast.
It is also a waste of sugar because 10% sugar will yield roughly 10% Ethanol at which point the yeast stop growing anyway. Special strains of yeast, like champagne and wine yeast, have stronger cell walls that protect them from the Ethanol -- so they grow longer.”
I’m not a chemist but I am a hobbyist. When I add more sugar than the recipe calls for to the mix, the CO2 output increases dramatically. It also doesn’t last as long (2 weeks instead of 3-4 weeks} That may in fact what the statement says.
I don’t know what your question is but I’d do a DIY CO2 search on AC and go by the recipes you find here.
Good luck,
Charles