Plants stop growing all together at 200ppm and lower. They slow a lot at anything over 1300ppm. So, most people aim for somewhere around 1100-1200ppm. However with no automatic sensors MANY people just do timed release of small doses of CO2. Ambient CO2 world wide is anywhere from 250ppm-350ppm. PLUS CO2 weighs more then regular air. thus FANS are needed to keep it up off the floor.

In a sealed room the yeast thing will fill up the room. YES it does work.

156 plants?? WOW. Little bigger then I assumed.:jointsmile: I'm in Colorado, US. With my 4 care takers, I can have a total of 24 plants!:wtf:

For that much space you'll need a lot of fans and a lot of kerosene lamps!
I'd suggest a natural gas CO2 generator. You can have it connected directly to your house/buisness's heating gas line and generate CO2 in MUCH larger areas. plus you don't have to haul fuel.