his point was merely that 99% of the veteran smokers/growers out there that have tried co2 have deducted that it's not worth the added costs, effort, and time.
I did it for three yrs, temps, and humidity are ALWAYS the limiting factor.
Water transpiration, and temps.
I had very, very slightly better yields, but it was negligible at best.
40lb tank, regulator, timed solenoid.
a perfect co2 setup would be outside, under the sun, in a sealed greenhouse, with a co2 generator providing heat and co2. Like an Alaskan grow or something, where temps aren't an issue
Dial in your ventilation, lights, and soil/growing media.
Do all that and those will get you better yields and end product much more substantially than adding co2 does.
I don't think you'll find any veteran grower that uses any yeast products for co2.
It won't get much more above the ambient PPMs of co2