You need to leave the fan on all the time as the Co2 is heavier than oxygen and will stay on the floor, the fan will move the air so the plants can use the Co2.
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