CO2 Emitter Systems
Marijuana Horticulture
by Jorge Cervantes
Compressed CO2 systems are virtually risk-free, producing no toxic gases, heat, or water. These systems are also precise, metering an exact amount of CO2 into the room. Carbon dioxide is metered out of a cylinder of the compressed gas using a regulator, flow meter, a solenoid valve, and a short range timer.
Two types of systems are: continuous flow and short range. Metal carbon dioxide cylinders which hold the gas under 1000 to 2200 pounds of pressure per square inch (psi) can be purchased from welding or beverage supply stores. The cylinders are often available at hydroponic stores. Tanks must be inspected annually and registered with a nationwide safety agency.
Welding suppliers and beverage suppliers often require identification such as a driver’s license. Most suppliers exchange tanks and refill them. Fire extinguisher companies and beverage supply companies normally fill CO2 tanks on the spot. If you purchase a lighter and stronger aluminum tank, make sure to request an aluminum tank exchange. Remember, the tank you buy is not necessarily the one you keep.
Buying a complete CO2 emitter system at a hydroponic store is the best option for most closet growers. These systems offer a good value for small indoor growers. You can make your own systems, but these systems often cost more than the pre-manufactured models.
Welding suppliers also carry regulators, and flow meters. Flow meters reduce and control the cubic feet per hour (cfh). The regulator controls the psi. Models with smaller flow rates, 10 to 60 cfh, are preferable for gardening purposes. buy a quality regulator-flow meter. Buy all components at the same time, and make sure they are compatible.
Carbon dioxide is very cold when released from a bottle where it has been kept under pressure. Even a quick blast can do damage to skin or eyes. If the flow rate is above 20 cfh, your regulator might freeze.
A regulator and flow valve are essential, but the solenoid valve and the timer are optional. However, growers who do not use a solenoid valve and timer waste CO2. The solenoid valve and timer regulate the flow of Co2. A solenoid valve is electrically operated and is used to start and stop the gas flow from the regulator and flow meter. The least expensive timer is plastic and is commonly used for automatic sprinkler systems.
Control the exact amount of CO2 released into the garden room by altering the flow and duration of CO2. To determine how long the valve should remain open, divide the number of cubic feet of gas required by the flow rate. If the flow meter is set at 10 cfh, the valve will need to be pen for 0.1 hours (1 divided by 10) or 6 minutes (0.1 hour x 60 minutes) to bring the room up to 1500 ppm. Remember, CO2 leaks out of the grow room. On average, the CCO2 level of the room returns to 300 ppm in abut three hours due to plant usage and room leakage. To maintain a steady level of CO2, split the amount of CO2 released per hour int two to fur smaller increments dispersed more frequently.
Distribute the CO2 from the tank to the grow room by using a tube or a fan. Suspend lightweight perforated plastic from the ceiling to disperse the CO2. The tubing carries CO2 from the supply tank to the center of the grow room. The main supply line is attached to several smaller branches that extend throughout the garden. CO2 is heavier and cooler than air and cascades onto the plants below.
To make sure the CO2 is dispersed from the tubing evenly, submerge the lightweight plastic tubing in water and punch the emission holes under water while the CO2 is being piped into the line. This way you know the proper diameter holes to punch and where to punch them to create the ideal CO2 flow over the garden.
Overhead fans help distribute CO2 evenly throughout the room. The CO2 is released directly below the fan into its airflow. This evenly mixes the CO2 throughout the air and keeps it recirculating across the plants.
Compressed CO2 is expensive, especially in large grow shows. At roughly $0.50 per pound, compressed gas is much more expensive than fuels used in generators. Cost of equipment and fuel make compressed CO2 enrichment systems less economical than generators.