I was reading and reading and reading...and finally someone said it...This is the BEST way to bring co2 to you're grow room. Because it's frozen it reduces heat which is a numer one problem, its cheaper then most any other co2 applications. gasses naturally drop in elevation so hang it in a bucket at the top of the room...obviously away form the exhaust fan.
But IMHO you don't need to mess with it, if you have good ventillation fresh air brings in all the co2 you need. and i have heard reports of co2 levels during flowering actually reducing the yield. As someone once said that I dearly trust. It is hand down the LAST thing that will be of benefit to your plant. There are a million other things you could spend your time researching and implementing to improve your garden