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.
Vancefish Reviewed by Vancefish on . CO2??? Flowering Now/ Temp Problem I have 47 PK plants growing is Sunshine Mix # 4 with 1/2 bag Peat Moss and 2 bags Perlite added. I use Safers Fish elusion and Mari cal Grow 20-20-20 . Lighting is 2 1000 lights. Plants are now 5 weeks old and are doing real well. I am putting them into 12/12 today. Is it to late to use CO2. I have taken 170 clones and the clones are doing OK.????? Should I introduce CO2 now, or forget it and wait until I plant the clones and start new grow.??? If I was to use CO2 I would use Coleman Camp Rating: 5