There are several economical delivery methods available to indoor growers. Carbon dioxide generators burn natural gas or compressed propane to produce carbon dioxide and water vapor. Carbon dioxide is also available at welding supply stores in compressed 5, 20, 35 and 50 pound tanks for refill. A tank regulator, infrared sensor and/or sequntial timer are necessary to release the carbon dioxide at proper intervals to maintain consistent levels.
Recommended carbon dioxide supplementation is between 1000 and 2000ppm, depending on light intensity, from germination or during the rooting of cuttings through final maturation. The leaves will develop larger stomata when undergoing development within a carbon dioxide supplemented atmosphere, increasing their ability to photosynthesize when fully developed. Suplementation delays maturation by keeping the plant's metabolism producing additional growth, instead of ripening. Use it throughout to the final moment and run it during the curing and drying process to further assist additional metabolization. This is accomplished using a Green Air Products digital ppm carbon dioxide controller connected to dual aluminum tanks. This system is the most accurate and flexible monitoring system.
Higher levels of carbon dioxide can be utilized under higher light conditions (above 50 watts/sqare foot), especially during vegetative growth when ambient temperatuires can be allowed to increase to 90 degrees. Carbon dioxide levels are maintained between 1600-2000ppm during vegetative and early flowering. When the buds begin to fill in, I lower ambient temperatures below 80 degrees and lower carbon dioxide levels to 1000-1200 ppm. Higher temperatures are necessary for the plant metabolism to increase and fully utilize higher levels of carbon dioxide, but will deteriorate cannabinoids in the resin glands.