Supplimental CO2 is only effective in an enclosed space, even moreso its only effective once you have maximized your plants growing potential to the point that they use all the ambient Co2 and thus to increase potential you need to add it. Most plants in most room get all the Co2 they can handle.
I dont mist my plants hardly ever, too easy to cause singing from HID hotspots when you spray them regularly, so i havnt used this technique but even thinking about c02 might be a few steps ahead of yourself unless your room is perfect and at the right temps, your nutes are at perfect levels, and your ventilation is set up to effectivly expose your co2 ammended air instead of just exhausting it.
