If you use Co2 you don't have to ventilate the place... The purpose of the ventilation is to bring more Co2 to the plants as the ambient air has about 20% of Co2. You still need to ventilate when the place is getting too hot because of the Co2 and the lamp but it's less often so there is not too much waste.
LuciferN Reviewed by LuciferN on . CO2 and ventilation Question. I would like to add CO2 to my grow tent and flower room but it doesnt sound practical with what ive read, because in order to properly ventilate your room u need to change the air in the room 2-5 times every minute. now any co2 u put in there litteraly goes right out the window. its like trying to heat your home in the winter with all the windows open... I am currently work with a 9x10x8ft room. 720sqft... so thats a pretty big fan i would need. plus im going to need a carbon scrubber. but Rating: 5