DK. This is gonna be a long post, and I hope you and the other subscribers to this thread don't mind. I have the book MARIJUANA Horticulture The Indoor/Outdoor MEDICAL Grower's Bible by Jorge Cervantes and I wanted to quote some it for yous guys... "Adding more CO2 to grow room air stimulates growth. Indoor cannabis cultivation is similar to conditions in greenhouse, and indoor growers apply the same principles. Cannabis can use more CO2 the 0.03-0.04 percent (300-400ppm) that naturally occurs in the air. By increasing the amount of CO2 to 0.12-0.15 percent (1200-1500 ppm)-the optimum amount widely agreed upon by professional growers-plants can grow up to 30 percent faster, providing that light, water, and nutrients are not limiting. Carbon dioxide enrichment has little or no affect on plants grown flourescent lights. Flourescent tubes do not supply enough light for the plant to process the extra available CO2.
Carbon doxide enrichment does not make plants produce more potent THC; it causes more foliage to grow in less time. The larger the volume of THC-potent cannabis, the larger the voume of THC-produced.
Carbon dioxide-enriched cannabis demands a higher level of maintenance than normal plants. Carbon dioxide-enriched plants use nutrients, water, and space faster than non-enriched plants. A higher temperature, from 75-80zf (24 to 26C) will help stimulate more rapid metabolism within the super-enriched plants. When temperatures climb beyond 85F (29C), CO2 enrichment becomes ineffective, and at 90F (32C) growth stops.
Carbon dioxide-enriched plants use more water. Water rises from plant roots and is released into the air by the stomata the plant uses to absorb the CO2 during transpiration. Carbon dioxide enrichment affects transpiration by causing the plants' stomata to partially close. This slows down the loss of water vapor into the air. Foliage on CO2 plants is measurably thicker, more turgid, and slower to wilt than leaves on non-enriched plants.
Carbon dioxide affects plant morphology. In an enriched growing environment, stems and branches grow faster, and the cells of these plant parts are more densely packed. Flower stems carry more weight without bending. Because of the increased rate of branching, cannabis has more flower initiation sites. Plants that sometimes do not bear from the first flower set are more likely to set flowers early if CO2 enrichment is used.
With CO2-enriched air, plants that do not have the support of the other critical elements for life will not benefit at all, and the CO2 is wasted. The plant can be limited by just one of the critical factors. For example, the plants use water and nutrients a lot faster, and if they are not supplied, the plants will not grow. They might even be stunted.
I honestly don't even know why I wrote that, but I hope it helps somebody out there.