Increasing CO2 levels in your cannabis garden will allow your plants to create more energy – if you provide adequate lighting as well. Again, light is the second requirement to create energy for your plants, meaning you must match your CO2 levels with your lighting. However, before we dive into how this is done, there are a number of other considerations to make before investing in a CO2 system.
CO2 levels in our atmosphere are around 400 ppm. Interestingly, studies show CO2 levels can continually increase plant growth as ppm reach upwards of 10,000. Note that once CO2 is above 3,000 ppm it starts to become dangerous for humans to breathe, and at 5,000 ppm it is considered lethal.
If you have a handle on the above points, you should be ready to try increasing your yields using added CO2.
The CO2 emitted should ideally fall from above the garden, as CO2 is heavy and will sink to the ground. Using fans will help keep the CO2 moving around the room and make it available for more plants to absorb. CO2 should only be emitted during the time that the lights are on; plants photosynthesize while it is dark out.
Compressed CO2 tanks can be acquired at hydroponic stores, compressed gas facilities, or even home brewing stores. In this case, the CO2 is produced by the manufacturers and is collected and compressed into tanks that can be then made available for purchase. This allows you to introduce controlled quantities of CO2 into your garden via emitters without having to own a CO2 generator. The benefit of this setup is that without a CO2 generator, you’re no longer producing heat when releasing CO2 into your garden. For this reason, compressed CO2 is ideal for smaller grow spaces.
CO2 generators, which look something like patio heaters, produce carbon dioxide by burning propane or natural gases. They can be set up to automatically power on or off when CO2 levels reach a specific ppm. Natural gas or liquid propane are very easy to acquire, but the burning of these gases produces heat which can be difficult to regulate in small grow spaces. Because of this, CO2 generators are better suited for large grow spaces with equipment for climate control.
Plants extract CO2 from the atmosphere via the plant’s stomates, which are the pores that plants “breathe” through. Photosynthesis begins as the plant uses CO2 in combination with light bulbs or light from the sun to produce both sugar and oxygen. The sugar is used by the plant to grow while the oxygen is released back into the atmosphere.
- Grow a healthy garden with a quality product
- Prevent and/or treat mold and pest infestations
- Set up a secure, sealed grow space
- Use an adequate high-powered light system
- Utilize quality strain genetics
- Use quality nutrients and growing mediums
Most gardeners have found that when you are producing high-quality light in your garden, a CO2 level of 1,200 to 2,000 ppm will increase the growth of your plant significantly. Additionally, when using CO2 your plants can handle a higher average temperature – around 85-90 degrees Fahrenheit. Be aware that if your CO2 levels are too high for the amount of light or heat generated in the garden, you will see your plants become damaged from excess CO2.
Learn how to add and control CO2 levels in your cannabis garden for stronger plants, increased yields, and the best possible end product.
by Bobby Mercer
For maximum plant growth, you want all of your CO2 released by the time you are 1/2 way to 2/3 of the way through this time period. If you have 10 minutes in between exhaust cycles, then it is a good idea to release all of the necessary CO2 within 5 minutes.
Attached to the solenoid is plastic tubing, often called laser tubing. It has very tiny holes manufactured in it (by lasers) that allow the CO2 to be evenly dispersed along the length of the tubing. Since CO2 is heavier than air, the tubing should be placed evenly around the garden above the tops of the plants. The only thing you have left to do is adjust the cubic foot per hour (CFH) of your flow control valve and set your timer, or else plug the solenoid into a digital CO2 controller.
Bobby- your grow room is still running a few degrees on the warm side. If possible, I would try ventilating the grow light with it’s own exhaust fan, pulling air from somewhere outside the room, through the enclosed light fixture, and exhausting it somewhere outside the room. If you are running your exhaust fan constantly to keep the room cool, this makes it very difficult to increase the CO2 levels inside the room. The best solution for CO2 supplementation is to have your grow room air conditioned, and the grow light ventilated separate from the rest of the room.
5 minutes is actually 1/12th of an hour. In order to release the necessary amount of CO2 in this time, you need to multiply the original flow rate in this example (.34) by 12. This gives you a flow rate of 4.08 CFH. Now you can set the flow control valve on your tank to 4.08 CFH, and set your timer to open the solenoid for 5 minutes immediately following the end of each exhaust cycle. The trick here is coordinating your exhaust fan with your CO2.
Your flow rate and the amount of time you take to release it share an inversely proportional relationship. This means if you take 1/6th of the time to release your CO2, then you will need to multiply your flow rate by 6/1 (which is simply 6) in order to end up with the same level of CO2 supplementation you began with.
Your garden is 7 x 5 x 8, which equals 280 cubic feet (the volume of your garden). CO2 levels in the atmosphere are normally around 300 ppm, and our goal is to bring the grow room up to 1500 ppm. Therefore, we need to increase the CO2 levels by 1200 ppm (or .0012). We calculate the amount of CO2 we need to release into the garden area by multiplying the increase (.0012) by the garden volume (280). In this example, we will need to release .336 cubic feet (CF) of CO2 to reach our goal of 1500 ppm. For convenience, I am rounding this number up to .34 CF.
In this example, if you set your flow control valve to .34 CFH, and programmed your timer to open the solenoid valve for one hour, you would slowly bring your grow room up to 1500 ppm CO2. This will only work if your exhaust fan does not kick on in the meantime to lower the room temperature. In reality, you should set your exhaust fan to kick on when the room reaches about 85 degrees, and to kick off when the garden reaches the ambient air temperature (hopefully about 65-75 degrees). Now, time how long it takes before the exhaust fan kicks on again.
Aluminum tanks are much lighter than steel tanks. 5 lb and 10 lb tanks will need to be re-filled very often, while 35 lb and 50 lb tanks are too heavy for most people to carry. For these reasons, I recommend a 20 lb aluminum tank for most indoor gardens. Having an extra tank (a backup) really comes in handy if you don’t want your garden to be without CO2 while you re-fill your only tank!
How to set up CO2 in your grow room. Step by step instructions on how to get the CO2 levels just right