No doubt everything was pretty dialed before adding CO2. It was one of the last things I added. Clearly one has to have a sealed room with environmental controls before using CO2.
My point is that CO2 is one of the only things I’ve ever added that increased both quality and quantity. No other product even comes close.
After learning about how C3 plants, like cannabis, use CO2 it makes sense how adding it can make such a difference. C3 plants use an enzyme RUBISCO to fixate CO2, but due to the shape often fixates O2 instead. Increasing the CO2 decreases the frequency of fixation O2, thus the plant can utilize more light.