When done right, adding CO2 can increase your yield 15 to 20%. In order to reap those benefits you have all the parameters fulfilled as far as environment and nutrition. Plants absorb CO2 through their stomata--small pores on the undersides of leaves. CO2 enrichment allows plants to open up their stomata and absorb more CO2. This maximizes plant growth by increasing transpiration, nutrient uptake, and also allows plants to tolerate higher temperatures by a few degrees.
There are a few different ways to produce CO2 for your grow space. The most efficient way to create large volumes of CO2 is a CO2 generator or burner. We recommend these systems for medium to large grow rooms. A CO2 burner burns either natural gas or liquid propane to produce CO2. One draw back to this method is the heat produced by burning gas.
Another method is to release CO2 from a pressurized CO2 tank. Standard sizes are 20 and 50 pound. A regulator is attached to the tank and a solenoid valve can be adjusted to release CO2. Small 3/16" inside diameter poly tubing comes off the regulator, which you can then feed directly above your plants (CO2 is heavier than air, so it falls) or behind a fan that is blowing over your plants. Regulators are often connected to timers that periodically turn them on and off. This CO2 calculator will help you calculate the setting on a CO2 regulator for your specific space. Referring to the CO2 calculator, Existing CO2 Levels are about 300 parts per million (ppm) and the Time Duration is how long you intend the CO2 regulator to be on per hour.
CO2 monitors constantly maintain the optimal level of CO2 for your environment by sensing the ppm of the ambient air and turning on your regulator as the ppm drops below a set level. CO2 monitors can be used with CO2 generators and CO2 regulators. As noted above, there is naturally around 300 ppm or part per million of CO2 in air. Adding any amount of CO2 will aid in faster plant growth, but 1500 ppm is the standard level of enrichment. Any higher level of CO2 will not have any added benefit and is unnecessary.
Growers who have small grow rooms and don't wish to purchase an expensive CO2 setup can always opt the Exhale bag. This bag has been inoculated with a mycelial mass (fungus) that produces CO2 naturally and lasts 6 months. Each Exhale bag produces enough CO2 for a 4 x 4 ft growing area or about three to six plants depending on their size.
CO2 enrichment is most efficient when in a sealed environment with minimal air exchange. More air flow in and out of your room allows for CO2 you are generating to be sucked out of the room. CO2 is heavier than ambient air so it will tend to fall and settle near the floor or your space. Oscillating fans are recommended to help stir up the air off the ground so it can be continually absorbed by your plants.