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CO2 Guide


New Member
In this guide I will cover how to determine how much Co2 you need to boost your grow room to maintain 1500 ppm. Methods are up to you and your budget.

Carbon dioxide (CO2) is used by plants in photosynthesis, or the conversion of water, atmospheric carbon dioxide and light in the plant's chloroplasts into food energy (simple carbohydrates), with oxygen as a byproduct. Resins and saps in the plants stems and branches then transmit this food around the plant to promote growth, reproduction and prevention of disease.

Photosynthesis stops at night, thus plants do not use CO2 during the night, or lights-out stage. Although enrichment of the atmosphere during the night cycle will not harm the plants, efficient CO2 systems are regulated so that when the lights go out, CO2 emissions stop.

Ambient air at sea level contains approximately 350-500 ppm of carbon dioxide. Higher altitudes and rural locations typically have a lower presence of CO2, while lowlands and urban areas have a higher presence.

Carbon dioxide enrichment involves increasing the concentrations of CO2 to 4-5 times the normal atmospheric levels, to between 1200-1500 ppm in an enclosed space. Enrichment has been shown to promote faster growth, higher yields, and stronger, healthier plants. Levels higher than 2000 ppm have been shown to retard plant growth. Low levels of CO2 (below 200) have been show to halt vigorous growth, even when all other conditions are ideal. Because of this, any enclosed space requires replenishment of the internal CO2 as it is used by plants, either from ventilation or from CO2 supplementation.

Temperature, humidity, and CO2 concentrations form a co-dependent relationship in a greenhouse or indoor grow. If all 3 factors are not in equilibrium, there is a risk to the plant in terms of stunted growth, toxicity, or death/disease. Most people who say they are not getting results are misusing the relationship of the three factors.

Standard growing conditions typically include concentrations of CO2 at 300-500 ppm, temperatures between 65-80°F, and relatively low humidity (20-40% rH). Studies have shown optimal growth and yields at 90-95°F, 1,500 ppm CO2, 45-50% relative humidity, 7,500-10,000 lumens/square foot of light, and vigorous air movement both above and below the canopy. CO2 enrichment under 80°F, under 7500 lumens/sf, or above 50% humidity is not recommended because plants will not be conducting photosynthesis quickly enough to benefit from the enrichment.

Internal air movement in the grow room is critical to CO2 enrichment. Carbon dioxide is a slightly heavier molecule than other molecules floating around in the gaseous mixture we call air. Thus, CO2 enrichment without air movement will result in the gas settling out of the atmosphere before it has a chance to reach the plants. High temps and humidity without air movement can also encourage mold and bacteria growth.

To calculate the amount of Carbon Dioxide needed to enrich a room to 1500 ppm, first calculate the volume of the growing space. For example we will use a 10 x 10 x 10 grow room. This means you have 1,000 cubic feet. Now lets figure how much CO2 needs to be present at anytime to maintain 1500 ppm.
1000 x 0.0015 = 1.5

This means you need 1.5 cubic feet of C02 to have 1500 ppm in this room.

Now we divide 1.5 by 8.5 = .176 (round up to .18) This means that 1.5 cf of Co2 weighs .18lbs

1 lb of CO2 is equal to about 8.5 cubic feet at normal temperature and atmospheric pressure.

All that is left is to find a system capable of delivering .18 lbs to the grow room in order to establish a ppm of 1500.

The rate at which carbon dioxide needs to be replaced is purely a function of how much ventilation the space receives and how many plants are consuming CO2 in the grow space. Only testing monitoring will ensure CO2 levels remain somewhat constant. Grow rooms that rely heavily on external ventilation to control temperatures or smell should not consider CO2 enrichment, because any gas introduced to the space will be blown out as quickly as it's created. A sealed room that relies on no external ventilation is ideal for CO2 enrichment. Since the ideal temperature for CO2 enrichment is much higher than normal, growers who employ this technique will need much less ventilation (if any).

Hope this helps


New Member
yes, however this is simple science found in books. Weights of gas and stuff like that and simple math to figure out the equations needed. So I basically pieced together information about the gas and applied it using math concerning how to determine what is needed to maintain that ppm


New Member
I need 1 cubic ft of CO2 for my growspace, how much baking soda and vinegar will produce a sufficient amt?
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