Seedlessone
Well-Known Member
CARBON DIOXIDE (CO2)
Carbon dioxide is an odorless gas and a minor constituent of the air we breathe. It comprises only .03 % (300 parts per million, or PPM) of the atmosphere but is vitally important to all life on this planet!
Plants are made up of about 80-90 % carbon and water with other elements like nitrogen, calcium, magnesium, potassium, phosphorous and trace elements making up only a small percentage. Almost all of the carbon in plants comes from this minor 300 PPM of carbon dioxide in the air.
Plants take in CO through pores, called stomata, in their leaves during daylight hours. They give off oxygen at the same time, the results of a process called photosynthesis. This oxygen that they give off is used by humans and all animal and marine life on this planet. Without it, animal and human life would not be possible.
Oxygen comprises almost 20 % of the earth's atmosphere. Most of it was generated by plant life. The process of photosynthesis combines CO2 and water to form sugars and free oxygen. Simple sugars like C6H12O6 provide plants with energy and are formed into the more complex plant parts such as carbohydrates, amino acids, protein, cellulose, leaves, roots, branches and flowers.
People and animals breathe in oxygen generated by plants and breathe out the CO2 that the plants needóa truly symbiotic relationship. In ancient times, millions of years ago, when there was only plant life on the earth and no animal life, the atmosphere was quite different. There was much more volcanic activity, one of nature's sources of CO2, and the air contained three to four times as much of it than now. Plants thrived. Giant tree ferns reigned supreme and much of our coal, gas and oil deposits were created by them during that long-ago time.
Plants would benefit from more CO2 in the air today, and actually are benefitting as we burn more fuels, one by-product being carbon dioxide. CO2 in the air has increased from 270 PPM to over 300 PPM, more than an 11% increase, in just the last 40 years! This has also worried many scientists because of what is called the greenhouse effect.. The more CO2 there is in the atmosphere, the higher the planet's temperature will go. Too much warming of the planet can melt ice caps, flood coastal cities, spread deserts and famine and drastically change the climate. This effect is somewhat self-regulating however. The oceans absorb a great deal of CO2 giving algae and plankton, 90% of the plant matter on earth, more CO2 to grow on and giving the rest of the plant matter on land more also. This decreases the amount of CO2 in the atmosphere, thereby regulating it. Scientists are just now learning to understand the self-regulating systems that stabilize most factors in our environment.
CO2 ENRICHMENT
Biologists and plant physiologists have long recognized the benefits of higher CO2 content in the air for plant growth. Horticulturists and greenhouse growers have used CO generators to enhance growth rates on plants for many years with good results.
With the advent of home greenhouses and indoor growing under artificial lights and the developments in hydroponics in recent years, the need for CO2 generation has drastically increased. Plants growing in a sealed greenhouse or indoor grow room will often deplete the available CO2 and stop growing. The following graph will show what depletion and enrichment does to plant growth:
Below 200 PPM, plants do not have enough CO2 to carry on the photosynthesis process and essentially stop growing. Because 300 PPM is the atmospheric CO content, this amount is chosen as the 100% growth point. You can see from the chart that increased CO can double or more the growth rate on most normal plants. Above 2,000 PPM, CO2 starts to become toxic to plants and above 4,000 PPM it becomes toxic to people.
With the advent of ideal growing conditions conditions provided by metal high-intensity discharge (H.I.D.) lighting systems, hydroponics, environmental controls such as temp., humidity, etc. and complete, balanced plant nutrients such as Ecogrow, the limiting factor on plant growth rate, quality, size and time to maturity becomes the amount of carbon dioxide available to the plants.
There are five common methods of generating extra amounts of CO2:
1. Burning hydrocarbon fuels
2. Compressed, bottled CO2
3. Dry ice
4. Fermentation
5. Decomposition of organic matter
We will discuss these five methods briefly in turn. In order to make an effective comparison of CO2 generation, benefits and drawbacks, a std. 8' X 8' X 8' or 512 cu. ft. growing area will be used.
1. BURNING HYDROCARBON FUELS:
This has been the most common method of CO2 enrichment for many years. A number of commercial growers and greenhouses use it in their larger structures. The most common fuels are propane, butane, alcohol and natural gas. Any of these fuels that burn with a blue, white or colorless flame will produce carbon dioxide, which is beneficial. If a red, orange or yellow flame is present, carbon monoxide is being generated due to incomplete combustion. Carbon monoxide is deadly to both plants and people in any but the smallest quantities. Fuels containing sulfur or sulfur compounds should not be used, as they produce by-products which are harmful.
Most commercial CO2 generators that burn these fuels are too large for small greenhouse or indoor grow room applications. Some small ones are avai fable or a Coleman lantern, bunsen burner or small gas stove can be used. All of these CO2 generators produce heat as a by-product of CO2 generation, which is rarely needed in a controlled environment grow room but may prove beneficial in winter growing and cool area greenhouses.
The rate of CO2 production is controlled by the rate at which fuel is being burned. In a gas burning CO2 generator using propane, butane or natural gas, one pound of fuel produces approximately 3 pounds of carbon dioxide gas and about 1.5 pounds of water vapor. Approximately 22,000 BTUs of heat is also added. These figures can vary if other fuels are used.
To relate this to our standard example in an 8' X 8' X 8' growing area, if you used ethyl or methyl alcohol in a gas lamp or burner at the rate of 1.3 oz. per day, we would enhance the atmospheric concentration of CO2 to 1300 PPM if the room was completely sealed.
An enrichment standard of 1300 PPM was chosen as it is assumed that 1500 PPM is ideal, and that the plants will deplete the available CO2 supply by 100 PPM per hour. Remember, the normal atmosphere contains 300 PPM of CO2. A 100% air exchange (leakage) every two hours is assumed to be the average air exchange rate in most grow rooms and tight greenhouses. If many cracks and leaks are present, this exchange rate will increase significantly, but added CO2 (above 300 PPM) will also be lost. If a vent fan is in use, disregard CO enrichment, as it will be blown out as fast as it is generated.
A circulation fan is beneficial, as it moves the air about in the greenhouse or grow room. If the air is still, it can cause a "depletion layer effect". This effect causes the CO2 right next to the plant leaf to be quickly depleted. If fresh air carrying additional CO is not brought to this surface, photosynthesis and growth will diminish and eventually cease.
There are a number of factors involved in keeping the CO2 content at the desired concentration level. 1. If the greenhouse or grow room is not tightly sealed up, add up to 50% to the CO2 generator production volume. 2. If temperature is increased fiom 70 F to 90 F, add 20% to the volume generated, and vice-versa. 3. If the grow area contains large or tightly spaced plants, add 20% to 30% to the CO2 volume generated.
If more light is used, more CO2 can be utilized and should be produced proportionately up to the practical limit of 5,000 footcandles per square yard and 1500 PPM CO2 atm. content. When more CO is generated, more water and plant nutrients should be used, again to a practical limit of 2X normal. lf your plants are going to grow faster because of CO2 enrichment, they will need more nutrient and water.
The last factor to consider in maintaining a set CO2 level is the size of your growing area. This is simply done for gas burning and following methods by setting up a mathematical ratio. In our "standard" room (8' X 8' X 8'), we have 512 cubic feet. If your growing area measures 10' X 10' X 20', you have 2,000 cubic feet of volume to contend with. If you want to use the ethyl alcohol/gas-lamp enrichment method, set up the ratio using l.3 oz. by weight of alcohol per day gives:
1.3 oz./day = 512 cu. ft.
------------------ -------------------
X oz./day = 2,000 cu. ft.
Then cross multiply: 512 X = 1.3 X 2,000. Dividing both sides by 512 gives you X = (1.3 X 2000)/512, solve for X. X = 5 oz.
You need 5 oz. of ethyl alcohol per day in a 10' X 10' X 20' grow area to generate the same amount (1300 PPM) of CO2 as in a 512 cu. ft. room.
To generate 1500 PPM above the available CO2 (200 PPM) in the same size area, set up the ratio:
1300 PPM = 5 ounces
-------------- ------------
1500 PPM = X
X = (5 X 1500)/1300 = 5.77 ounces.
NOTE: One pound of CO is equivalent to approximately 8.7 cu. ft. of gas at standard temperature and pressure.
If different hydrocarbon fuels are used, the heat content, in terms of B.T.U. should be taken into account. If the BTU per hour rate is half that of ethyl alcohol, twice as much must be burned to generate the same approximate amount of CO2 desired. The amount of CO2 generated depends on the carbon content of the fuel being used. The BTU per hour heat content can be obtained from literature or suppliers.
Carbon dioxide is an odorless gas and a minor constituent of the air we breathe. It comprises only .03 % (300 parts per million, or PPM) of the atmosphere but is vitally important to all life on this planet!
Plants are made up of about 80-90 % carbon and water with other elements like nitrogen, calcium, magnesium, potassium, phosphorous and trace elements making up only a small percentage. Almost all of the carbon in plants comes from this minor 300 PPM of carbon dioxide in the air.
Plants take in CO through pores, called stomata, in their leaves during daylight hours. They give off oxygen at the same time, the results of a process called photosynthesis. This oxygen that they give off is used by humans and all animal and marine life on this planet. Without it, animal and human life would not be possible.
Oxygen comprises almost 20 % of the earth's atmosphere. Most of it was generated by plant life. The process of photosynthesis combines CO2 and water to form sugars and free oxygen. Simple sugars like C6H12O6 provide plants with energy and are formed into the more complex plant parts such as carbohydrates, amino acids, protein, cellulose, leaves, roots, branches and flowers.
People and animals breathe in oxygen generated by plants and breathe out the CO2 that the plants needóa truly symbiotic relationship. In ancient times, millions of years ago, when there was only plant life on the earth and no animal life, the atmosphere was quite different. There was much more volcanic activity, one of nature's sources of CO2, and the air contained three to four times as much of it than now. Plants thrived. Giant tree ferns reigned supreme and much of our coal, gas and oil deposits were created by them during that long-ago time.
Plants would benefit from more CO2 in the air today, and actually are benefitting as we burn more fuels, one by-product being carbon dioxide. CO2 in the air has increased from 270 PPM to over 300 PPM, more than an 11% increase, in just the last 40 years! This has also worried many scientists because of what is called the greenhouse effect.. The more CO2 there is in the atmosphere, the higher the planet's temperature will go. Too much warming of the planet can melt ice caps, flood coastal cities, spread deserts and famine and drastically change the climate. This effect is somewhat self-regulating however. The oceans absorb a great deal of CO2 giving algae and plankton, 90% of the plant matter on earth, more CO2 to grow on and giving the rest of the plant matter on land more also. This decreases the amount of CO2 in the atmosphere, thereby regulating it. Scientists are just now learning to understand the self-regulating systems that stabilize most factors in our environment.
CO2 ENRICHMENT
Biologists and plant physiologists have long recognized the benefits of higher CO2 content in the air for plant growth. Horticulturists and greenhouse growers have used CO generators to enhance growth rates on plants for many years with good results.
With the advent of home greenhouses and indoor growing under artificial lights and the developments in hydroponics in recent years, the need for CO2 generation has drastically increased. Plants growing in a sealed greenhouse or indoor grow room will often deplete the available CO2 and stop growing. The following graph will show what depletion and enrichment does to plant growth:
Below 200 PPM, plants do not have enough CO2 to carry on the photosynthesis process and essentially stop growing. Because 300 PPM is the atmospheric CO content, this amount is chosen as the 100% growth point. You can see from the chart that increased CO can double or more the growth rate on most normal plants. Above 2,000 PPM, CO2 starts to become toxic to plants and above 4,000 PPM it becomes toxic to people.
With the advent of ideal growing conditions conditions provided by metal high-intensity discharge (H.I.D.) lighting systems, hydroponics, environmental controls such as temp., humidity, etc. and complete, balanced plant nutrients such as Ecogrow, the limiting factor on plant growth rate, quality, size and time to maturity becomes the amount of carbon dioxide available to the plants.
There are five common methods of generating extra amounts of CO2:
1. Burning hydrocarbon fuels
2. Compressed, bottled CO2
3. Dry ice
4. Fermentation
5. Decomposition of organic matter
We will discuss these five methods briefly in turn. In order to make an effective comparison of CO2 generation, benefits and drawbacks, a std. 8' X 8' X 8' or 512 cu. ft. growing area will be used.
1. BURNING HYDROCARBON FUELS:
This has been the most common method of CO2 enrichment for many years. A number of commercial growers and greenhouses use it in their larger structures. The most common fuels are propane, butane, alcohol and natural gas. Any of these fuels that burn with a blue, white or colorless flame will produce carbon dioxide, which is beneficial. If a red, orange or yellow flame is present, carbon monoxide is being generated due to incomplete combustion. Carbon monoxide is deadly to both plants and people in any but the smallest quantities. Fuels containing sulfur or sulfur compounds should not be used, as they produce by-products which are harmful.
Most commercial CO2 generators that burn these fuels are too large for small greenhouse or indoor grow room applications. Some small ones are avai fable or a Coleman lantern, bunsen burner or small gas stove can be used. All of these CO2 generators produce heat as a by-product of CO2 generation, which is rarely needed in a controlled environment grow room but may prove beneficial in winter growing and cool area greenhouses.
The rate of CO2 production is controlled by the rate at which fuel is being burned. In a gas burning CO2 generator using propane, butane or natural gas, one pound of fuel produces approximately 3 pounds of carbon dioxide gas and about 1.5 pounds of water vapor. Approximately 22,000 BTUs of heat is also added. These figures can vary if other fuels are used.
To relate this to our standard example in an 8' X 8' X 8' growing area, if you used ethyl or methyl alcohol in a gas lamp or burner at the rate of 1.3 oz. per day, we would enhance the atmospheric concentration of CO2 to 1300 PPM if the room was completely sealed.
An enrichment standard of 1300 PPM was chosen as it is assumed that 1500 PPM is ideal, and that the plants will deplete the available CO2 supply by 100 PPM per hour. Remember, the normal atmosphere contains 300 PPM of CO2. A 100% air exchange (leakage) every two hours is assumed to be the average air exchange rate in most grow rooms and tight greenhouses. If many cracks and leaks are present, this exchange rate will increase significantly, but added CO2 (above 300 PPM) will also be lost. If a vent fan is in use, disregard CO enrichment, as it will be blown out as fast as it is generated.
A circulation fan is beneficial, as it moves the air about in the greenhouse or grow room. If the air is still, it can cause a "depletion layer effect". This effect causes the CO2 right next to the plant leaf to be quickly depleted. If fresh air carrying additional CO is not brought to this surface, photosynthesis and growth will diminish and eventually cease.
There are a number of factors involved in keeping the CO2 content at the desired concentration level. 1. If the greenhouse or grow room is not tightly sealed up, add up to 50% to the CO2 generator production volume. 2. If temperature is increased fiom 70 F to 90 F, add 20% to the volume generated, and vice-versa. 3. If the grow area contains large or tightly spaced plants, add 20% to 30% to the CO2 volume generated.
If more light is used, more CO2 can be utilized and should be produced proportionately up to the practical limit of 5,000 footcandles per square yard and 1500 PPM CO2 atm. content. When more CO is generated, more water and plant nutrients should be used, again to a practical limit of 2X normal. lf your plants are going to grow faster because of CO2 enrichment, they will need more nutrient and water.
The last factor to consider in maintaining a set CO2 level is the size of your growing area. This is simply done for gas burning and following methods by setting up a mathematical ratio. In our "standard" room (8' X 8' X 8'), we have 512 cubic feet. If your growing area measures 10' X 10' X 20', you have 2,000 cubic feet of volume to contend with. If you want to use the ethyl alcohol/gas-lamp enrichment method, set up the ratio using l.3 oz. by weight of alcohol per day gives:
1.3 oz./day = 512 cu. ft.
------------------ -------------------
X oz./day = 2,000 cu. ft.
Then cross multiply: 512 X = 1.3 X 2,000. Dividing both sides by 512 gives you X = (1.3 X 2000)/512, solve for X. X = 5 oz.
You need 5 oz. of ethyl alcohol per day in a 10' X 10' X 20' grow area to generate the same amount (1300 PPM) of CO2 as in a 512 cu. ft. room.
To generate 1500 PPM above the available CO2 (200 PPM) in the same size area, set up the ratio:
1300 PPM = 5 ounces
-------------- ------------
1500 PPM = X
X = (5 X 1500)/1300 = 5.77 ounces.
NOTE: One pound of CO is equivalent to approximately 8.7 cu. ft. of gas at standard temperature and pressure.
If different hydrocarbon fuels are used, the heat content, in terms of B.T.U. should be taken into account. If the BTU per hour rate is half that of ethyl alcohol, twice as much must be burned to generate the same approximate amount of CO2 desired. The amount of CO2 generated depends on the carbon content of the fuel being used. The BTU per hour heat content can be obtained from literature or suppliers.