In one final twist of irony, as you begin to increase carbon dioxide levels to maximize plant growth you will reach a point where temperature becomes the limiting factor. In order to benefit from the highest levels of CO2 supplementation (1500-2000 ppm), you actually need to run your garden area warmer than normal (80-85 degrees). On average, plants will also require an extra 30 watts of light/sq.ft. (80-100 watts/sq.ft.). Plants will use extra water and nutrients under these conditions, so make sure they are available!