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Atmosphere FAQ

What are the benefits of adding CO2 to my grow room?

Many growers overlook the huge importance of CO2 to fast growing plants. CO2, along with light, are the two most important sources of food for plants. Plants take light and CO2, and through a process called photosynthesis, produce food for themselves. The nutrients that growers feed their plants are kind of like the salt and pepper, whereas the light and CO2 are like the meat and potatoes. The nutrients are necessary for photosynthesis to occur, but they are mainly a catalyst to allow the reactions to take place. In fact, if you were to analyze any plant, you would find that it consists of over 90 percent water, a few percent nutrients, and the rest is carbon.

Normal CO2 levels are between 300 to 500ppm (parts per million), depending on whether you live in an urban or rural area (we have almost 600ppm of CO2 here in Los Angeles!). Increasing these levels to 1500ppm can often have dramatic effects on your plants, including faster growth rates and increased yields. This is why it is so important to always have fresh air circulating into your grow room, or better yet, add supplemental CO2.

What are the most common ways of adding CO2?

The two most common devices used to produce CO2 are CO2 generators and bottled CO2.

Bottled CO2:

Bottled CO2 is perfect for small areas up to around 12' x 12' x 8'. CO2 tanks are available in several different sizes, but the two most common sizes used for enriching grow rooms are 20# and 50#. When full, a 50# tank weighs a considerable amount; even a very strong person will need a dolly to transport it. CO2 tanks can be filled at most welding and dry ice companies. Keep in mind before you bring your shiny new tank to a welding company that many of them will exchange your empty tank for a used full one rather than filling it up, so make sure to ask first. Most places will charge less than $20 to fill a 20# tank and $50 for a 50#. In addition to the CO2 tank, you will also need to purchase a CO2 Enrichment System to properly dispense the CO2. The enrichment system attaches directly to the CO2 tank with either a wrench or channel locks. Most enrichment systems consist of a pressure regulator and gauge, a solenoid valve, and a flow meter. The flow meter allows you to adjust the amount of CO2 coming out of the tank, and the solenoid valve allows you to attach a timer or other device to turn on and off the flow of CO2, thereby maintaining the desired level of CO2 (usually between 1500 and 2000ppm).

CO2 Generators:

CO2 Generators are generally a little more expensive than CO2 tanks and also produce a small amount of heat, but they offer several advantages. Generators operate on either propane or natural gas, both of which are less expensive and easier to come by than bottled CO2. Propane generators can operate using just about any propane tank, including the small ones used for barbeque grills. Some growers use the natural gas hookup provided for a gas dryer in their house to attach natural gas generator, which not only saves the labor of swapping out empty propane tanks, but also saves them money, as natural gas is much cheaper than propane. Some generators, such as the MegaGrowth, are vented so that you can attach an exhaust fan and eliminate some of the heat they produce.

Regardless of which solution you choose (bottled CO2 and an enrichment system or a CO2 generator), you will still need something to control it. Keep reading for information on how to accomplish this.

When and how often do I need to use CO2?

C02 should only be used when your lights are on, as plants only use CO2 during photosynthesis. C02 is most effective during the flowering stage, but BGH recommends using CO2 throughout the life of your plants for maximum results.

How do I keep my room from getting too hot?

Heat buildup in a grow room is a common problem among growers. We usually advise our customers not to go crazy and spend lots of money from the get go, but instead take it in stages. Start with the cheapest and simplest solutions first and graduate to more expensive and complicated one's if the problem persists. Proper planning of the grow room can make things a lot easier. Make sure that you have not only installed an adequate exhaust fan, but also make sure you have sufficient intake, otherwise your fan will not be able to do its job properly. In most cases, you will not need to use a fan for the intake, an adequate size opening in the room will do.

The next step towards cooling your room is to cool your lights. Most of the lighting systems and reflectors we carry have air-cooling options that allow you to hookup your exhaust fan directly to your reflector, eliminating the heat right at the source. Almost all air-cooled reflectors have to two vent openings. Many growers will simply attach their exhaust fan to one of the ducts with some duct hose so that the hot, stale air in the grow room will be sucked out along with the hot air in the reflector that is generated by the bulb. If you are using CO2, then you will want to suck air from an outside source, through the reflector, and back outside again so that you do not suck out any of the CO2-rich air from the grow room. This scenario also applies if you end up having to use an air conditioner, since you don't want to suck out the cool, air conditioned air. Most air conditioners have a vent which you will want to close so that it recirculates the air in the room instead of constantly sucking in air from the outside, especially if the air outside is hot.

If, after venting your room and installing an air conditioner, you still can't get rid of the heat problem, you may need to consider water-cooling your lights. See the lighting section for products such as the Hydro Coil Water-Cooling Jacket for more information on water-cooling.

What is the ideal temperature range for plants?

Air temperature within the grow room should be between 77 and 83 degrees Fahrenheit. Water temperature should be between 68 and 72 degrees Fahrenheit.

What size fan do I need to vent my room?

Due to the many variables that have to be considered, there is no exact answer or formula available to determine the fan size. But, we will at least try narrow things down as much as possible so that you can make an educated guess. The old rule of thumb is to try to replace the volume of air in your room at least once every 5 minutes. Based on years of experience, BGH feels that you should try to replace it every 1 to 3 minutes if you are trying to cool your room as well as vent it. The formula used to determine the volume of your room in cubic feet is to multiply length x width x height, so a 10’ x 10’ x 8’ room would be 800 CF. Divide this number by 5 and you will have the minimum CFM (cubic feet per minute) fan required to vent your room (in this example – 160 CFM).



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