Blazed from what I have read, which is a great deal on this very subject because it was originally in my plans you need following.

Got to get temps up for plants to use the C02 for starters.

Seems as if all who explain setup do the 2 hour cycle. Meaning they bring in fresh air which contains ~300 PPM of C02, then their controller adds enough from a burner or tank that ups to ~1500PPM. Then for the 2 hour period the controller adds as needed to hold that level.

Then, at end of the 2 hour period, you "exchange" all the air in the room, bring in more fresh air, add C02 again, and repeat.

Not being able for you to exchange the air would do uhhhh, I dont know. Ya need Zandor or one of the true grow gurus to assist ya with this.

So, there are other conditions that you need to have tweaked and working efficently to do this the right way is my take. (sealed room, HID lights of course, right temp, etc) Need fans blowing upwards, feed from top. C02 heavier than air.

When done properly it must be worth all you need to do. For me, I am perfectly content with what I get now. I dont need C02 burner (which for some reason scares the shit out of me) or a tank to worry about keeping filled.

All in all I most likely didnt tell you a fucking thing you didnt already know, but I cant sleep and felt like typing..........


Best of luck,
b0nger