Quote Originally Posted by copobo
CO2 is not called for in veg. It must be a closed room as TurboALLWD said or your just throwing money away.

CO2 is really for flowering, should only be run when the lights are on. A common setup is to use a controller, set ppm to 1500, and top temp to be 90. Then, the controller will come on and dump the air in the room, and when finished, bring ppm back to 1500. Plants like it hotter when there is CO2, and can tolerate and thrive in higher temps.

CO2 should be NOT be run the last 2-3 weeks as your buds will not swell.

hth
How do you not use co2 the last 2-3 weeks if you have plants at different maturities in flower at the same time, i.e., a perpetual harvest set-up?
senorx12562 Reviewed by senorx12562 on . Need Co2 advice Just picked up a tank of Co2 and a regulater and need to know when and how it will work best...setting etc. want to try to do it right the first time for sure.. lites run about 18 hours a day in this room. We strung some 3/16 hose into the T5 room and drilled holes about 2 inches apart under the T5..when would be the best time to run Co2 in this room ? also do we need to turn the fans and can fan off when we turn the Co2 on..? Main grow room under the 1000 sodium lite we where Rating: 5