everybodys gonna try to tell you crazy ways to get co2.. and you can try them.. but when it comes down 2 it.. tank and regulator is the only real way to get controled co2 to your plants.. all the other ways will fall short..
the plant obsorbes the carbon out of the co2, more carbon = more growth @ yeald... 1500 ppm = ideal amount of co2.... the average amount in the air is around 300 ppm...So you can see how do it yourself co2 setups are just not even gonna be worth the time... Warmer temps are also needed with higher co2, 80 - 85 F plus an extra 30w of light per sqft
i saw a co2 setup with a tank, regulator and a electric valve on a timer.. the guy opend the valve and watchd the ppm untill it was at 1500 over the entire grow room and closed it... he timed it from open to close and then set his timer to open the valve for that long 3 times a day... at the same time the room was filling with co2 the exaust fans were cut off... then after awhile they cut back on to air it out before the next cycle.. perfect co2 setup