Humidity, ventilation, and CO2 control equipment are critical for hydroponic gardening.
Let's first start with understanding Carbon Dioxide (CO2). CO2 is odorless, and colorless so caution is critical. CO2 gas, never-the-less is essential for plant life; and indoor gardening such as in Hydroponic gardening requires CO2 generators , as well as humidity and temperature controllers to provide optimum plant growth environment.
Carbon dioxide is absorbed by the plants and during photosynthesis the CO2 is is split into it's basic elements, carbon and oxygen. Small amounts of oxygen are used by the plant but most of the oxygen are released back into the atmosphere. The carbon is combined with water (H2O) in the presence of light to form a sugar molecule. The plants then convert the sugar into carbohydrates. When the plant absorbs nutrients (primarily nitrogen from the roots) they are combined with the carbohydrates to form new plant tissue. This process is called photosynthesis. The entire process is only as good as its weakest link. If any of the required ingredients (light, CO2, water and nutrients) are at a level below that which the plant can use for maximum efficiency, the plant will not perform at it's full potential. In other words, if you inject CO2 into a system that is not receiving enough light or nutrients the results will be disappointing.
There are several conditions that must be met for the plants to be able to use the increased CO2 levels properly. The most important is lighting. Light levels must be very high (more than 20 watts per square foot) or there will be little or no increase in plant growth rates. The plants will like slightly higher temperatures than normal (approx. 3 - 5 degrees higher). The plants will also metabolize water and nutrients faster, so reservoirs may need a little more attention.
Plants can absorb and process very large amounts of CO2. There is usually about 300 to 600 p.p.m. (parts per million) of CO2 in the atmosphere. Most plants can use 1500 p.p.m. in optimum growing conditions. When using elevated levels of CO2 the growth rate can be increased by as much as 100% to 200%. Most studies report increases in the 40% to 50% range.
The ideal situation would be to keep the CO2 levels at optimum at all times. This would require constant injection of low levels of gas (constantly replacing what the plants are using). This is not practical in most situations as venting of the growing environment is often needed to control heat build up. In these cases CO2 injection should be done immediately following venting.
The biggest problem that people encounter when using CO2 is that they get carried away, they wrongly think that a little is good so a lot is better. When CO2 levels approach 2000 p.p.m. most plants will die. High levels of CO2 are also toxic to humans, primarily due to oxygen deficiency. Before injecting CO2 the room should be vented to remove excess CO2 that might be left over from the previous injection, this prevents the build up of CO2 that could harm the plants.
There are several ways to get extra CO2, the two most common are using bottled CO2 and using CO2 generators. These are the automated ways to add CO2 to the growing environment. Getting precise control of the CO2 levels in your growing environment can be rather expensive, CO2 monitors are the best method, these monitors keep a constant reading of the C levels and automatically adds gas when needed.
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