You'd still probably want to consider adding an exhaust fan to the setup, if for nothing else, than to control the smell brought on by flowering. Intake could be as simple as opening a window in the same room, or having a strong inline fan blowing fresh air from an open window into the area that the growspace is located. Good circulation of air keeps plants healthier. Pockets of stale, warm air can form in unventilated grow rooms, and are no good for the plants. On another note, you're not going to get as much fresh air into the growspace as you would if you were using a strong intake fan to bring in the fresh air directly.

As for carbon dioxide supplementation, I prefer using a small amount every day using a tank & regulator. I've yet to do any experiments where a constant supply of enriched CO2 is supplemented...namely because of the inherent cost of running such a setup. If you plan on running a system that supplements CO2, you really should have the entire space sealed...so as to prevent leakage of the precious gas into other rooms of your house, attic, etc. As I said, it isn't cheap, so you'll be careful not to waste it. Also, you don't want your fans to blow directly at the plants at the same time the regulator releases the gas, or you'll just end up dispersing it everywhere BUT onto the plant(s).

But, by making sure the growroom (no matter how small) has adequate ventilation, in essence you'll be supplying a constant - albeit, minimal - supply of CO2. This is generally enough for small to modest grows.

Hope that helps.
Mr. Clandestine Reviewed by Mr. Clandestine on . Is intake and exhaust required with envirolites(200w)? High, I've got a project with 7 lowryder no.2's in a 60cmx120cm, 200cm tall growroom, I'll be using one 200w envirolite(white spectrum) until flowering starts, then add another one with red spectrum, use these until harvest. My question is, as these envirolites shouldn't produce much heat, will I be needing intake and exhaust? There would be one or two fans blowing towards the lamps and Co2 will be given with these: No Mercy Supply . I'll be turning the lights off for one hour each day Rating: 5