Marijuana Horticulture: The Indoor/Outdoor Medical Grower's Bible

are less expensive to maintain and less cumbersome, but they have some disadvantages, too. One pound of fuel produces 1.5 pounds of water and 21,800 Btu of heat. For grow rooms less than 400 cubic feet, this makes generators unusable. Even for larger garden rooms, the added heat and humidity must be carefully monitored and controlled so as not to affect plants. Growers in warm climates do not use generators, because they produce too much heat and humidity.
     
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    1 pound of CO 2 displaces 8.7 cubic feet (246 cm 3 ) of CO 2 .
    0.3 pound (0.135 kg) of fuel produces 1 pound (454 gm) of CO 2 .
    Divide the total amount of CO 2 needed by 8.7 and multiply by 0.33 to determine the amount of fuel needed. In our example we found we need 1 cubic foot of CO 2 for an 800 cubic foot garden room.
    L × W × H = room volume (cubic feet)
    12 × 14 × 8 = 1344 cubic feet (38 m 3 )
    Desired CO 2 level is 1200 ppm (0.0012 ppm)*
    Multiply room volume by 0.0012 = desired CO 2 level
    1344 cubic feet (38 m 3 ) × 0.0012 = 1.613 cubic feet (46 cm 3 ) CO 2
    1 pound (0.45 kg) of fuel burned = three pounds (1.35 kg) of CO 2 gas
    0.33 pound (0.148 kg) fuel burned = one pound CO 2 gas
    0.33 × 1.613 = 0.56 pounds of CO 2 fuel to burn to bring the CO 2 level to 1200 ppm.
    Three times this amount (0.53 × 3 = 1.59 pounds) of fuel will create enough CO 2 for the room for 12-18 hours.
    Convert this into ounces by multiplying by 16 (there are 16 ounces in a pound). .037 × 16 = 0.59 ounces of fuel are needed for every injection.
    Check out www.onlineconversion.com to convert to or from the English and Metric Systems.
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    If fuel does not burn completely or cleanly, CO 2 generators can release toxic gases–including carbon monoxide–into the grow room. Nitrous oxide, also a byproduct of burning propane, can grow to toxic levels, too. Well-made CO 2 generators have a pilot and timer. If leaks or problems are detected, the pilot and timer will turn off.
    A CO 2 monitor is necessary if you are sensitive to high levels of the gas. Digital alarm units or color change plates (used in aircraft) are an economical alternative. Carbon monoxide is a deadly gas and can be detected with a carbon monoxide alarm available at most hardware and building supply stores.
    Check homemade generators frequently, including kerosene or gas heaters. Propane and natural gas produce a blue flame when burning efficiently. A yellow flame means unburned gas (which creates carbon monoxide) and needs more oxygen to burn cleanly. Leaks in a system can be detected by applying a solution of equal parts water and concentrated dish soap to all connections. If bubbles appear, gas is leaking. Never use a leaky system.
    Oxygen is also burned. As it becomes deficient in the room, the oxygen/fuel mixture changes. The flame burns too rich and yellows. This is why fresh air is essential.
    Turn off CO 2 generators at night. They create excess heat and humidity in the grow room, and they need oxygen to operate. At night, roots need the extra oxygen in the room for continued growth.
    If you are using CO 2 and the yield does not increase, check to make sure the entire grow room is running properly and that plants have the proper light and nutrient levels, as well as the correct temperature, humidity, grow-medium moisture, and pH. Make sure roots receive enough oxygen both day and night.
Other Ways to Make CO 2
    There are many ways to make CO 2 . You can enrich small areas by burning ethyl or methyl alcohol in a kerosene lamp. Norwegians are studying charcoal burners as a source of CO 2 . When refined, the system will combine the advantages of generators and compressed gas. Charcoal is much less expensive than bottled CO 2 and is less risky than generators in terms of toxic by-products. Others are studying the use of new technology to extract or filter CO 2 from the air.
    This little inexpensive puck called Excellofizz ( www.fearlessgardener.com ) releases CO 2 into the atmosphere. It is simple to use; just add a few ounces of water and a puck or two to cause a chemical reaction that will disperse enough CO 2 to augment the air in a 10-foot-square (9 m 2 ) room to about 1000 ppm all day. It also releases a eucalyptus fragrance to help mask odors. Make sure to keep the fizz contained, and if using an ozone generator, keep the lamp clean.
Compost and Organic Growing Mediums
    Decomposing organic materials like wood chips, hay, leaves, and manures release large amounts of CO 2 . Although you