I think I saw the same video Tomthehippie saw ("I Grow Chronic!"). There is a guy who is painted green and he shows you how to setup a quality grow room in a basement. He has HID lighting along with CO2 tanks, regulators, timers, the whole bit. He said:

"If I didn't have money for this" says green man talking about the CO2 system, "Well I would just use bubbly water and a sprayer, I can spray this on the plants and they will get CO2 all day long, actually, I do both."

He uses a CO2 system and a sprayer combined, just passing on a bit of info I came across about this subject:thumbsup: