Carbon dioxide (CO2) is fundamental to facilitate the growth of plants, and it is particularly relevant to the course of photosynthesis, as plants use CO2 to turn light into energy to grow. Without CO2, plants would die. Luckily, there is almost always CO2 floating in the air. It is odourless and colourless, and you are most likely breathing it in small amounts right now.
Providing more carbon dioxide in your grow room offers benefits to plants in ways that improves plant health and development. Plants use CO2 to "breath". It helps them photosynthesize, which is how plants convert light energy into food for themselves.
Plants nurtured with the effects of CO2 typically are stronger and more vibrant. These qualities are often characterized by stronger roots, bigger dark green leaves, and considerably more fruits and flowers when compared with plants with insufficient carbon dioxide. This is because in high light situations, such as being under grow lights, there is often more light than the plant can use. By providing it with extra CO2, the plant can use more light than it naturally would be able to.
Fun fact: Research has shown that when C3 plants (a form of photosynthesis that 95% of the plants on earth use, including cannabis) are exposed to higher concentrations of CO2, the plants will produce thicker leaves.
Levels of CO2 are measured in PPM (Parts Per Million). If you have sufficient air circulation in your home and growing area, you can expect your CO2 concentration to be around 300- 400 PPM. If your growing area was to go below 200 PPM of CO2, your plant would stop growing. This is because it doesn't have enough CO2 to photosynthesis, which means it is not receiving energy from the light. Studies have shown that when CO2 concentrations are around 1500 PPM, plant growth will be accelerated. This can result in bigger yields.
An added bonus is if you keep your growing area around 1000-1200 PPM of CO2, your plant can tolerate higher temperatures, so if your lights produce a lot of heat, your plant will tolerate it better.
Adding carbon dioxide to your plants is proven to increase yields, but due to the high cost of implementing these systems, it is not a necessary practice.
How to Produce Surplus CO2 for in House Growing
There are multiple ways to produce surplus CO2, however, there are only two techniques that offer considerable levels of convenience and efficiency.
These techniques are CO2 tanks, and CO2 generators. They are the most effective and advisable techniques to increasing CO2.
Before you start with injecting CO2 into your growing space, you need to make sure that your space is completely sealed so that outside air can’t get in and disturb the CO2.
However, you still need to vent out heat produced by grow lights. To ensure that you don’t accidentally vent out CO2, you can separate air from CO2 in your grow space by setting up cool tubes or hooded reflectors. If using a Grobo, no need to worry about this! Our LEDs don't get hot and the unit comes with built in fans.
This is an image of what the setup would look like using cool tubes and an exhaust tube attached to the grow light.
Grow light in a cool tube
Here is a diagram explaining how sealing your grow light works to ensure no CO2 escapes.
Using CO2 Tanks
This approach to producing surplus carbon dioxide involves filling tanks saturated with CO2. The use of CO2 tanks in carbon dioxide augmentation is simple, effective, and is a preferred starting option.
For convenience, the CO2 tanks should be located outside the growing space, and should be connected to the growing tent through a pump that feeds into the growing area.
It is important that the pump is elevated above the plant. Carbon dioxide is a bit thicker than oxygen, and it will sink to the bottom of your growing area. As such, it should be placed in a position where the CO2 can rain down on the leaves.
Fun fact: Absorption of CO2 is done by the stomata of plant leaves. Stomata are tiny openings in the plant cells that allow for gas exchange. Basically, plants have thousands of tiny openings (stomata's) in replacement of lungs. This is how they breathe!
Additionally, one of the biggest advantages of CO2 tanks is the fact that it can regulate the amount of CO2 emitted into the grow house for maximum results.
Regulation is done through the use of a pressure controller. These controllers are structured to release the required amount of CO2 in the grow area automatically.
While the advantages of CO2 tank outweigh the disadvantages, it is necessary to carefully evaluate the disadvantages.
Some problems with the tank system is that it can get expensive, and there is always the possibility of tanks exploding when exposed to an open flame.
Also, it is imperative to take note of the fact that the air produced by CO2 can be harmful to people and animals, and must not be inhaled, as it could cause respiratory and health issues. A good precautionary measure is to shut down tanks before focusing on other activities in the grow room, and to keep a close eye on the PPM.
Using CO2 Generators
A CO2 generator is the second effective option to producing adequate CO2 for indoor growing, and it operates by burning propane or gas. Just like CO2 tanks, the CO2 generator is expensive, with an inside burning system that is sealed.
It's important to monitor temperature when using a CO2 generator in a small indoor growing facility because it increases moisture quickly in comparison to a roomy indoor facility.
Other techniques to produce carbon dioxide would encompass dry ice, compost bags, fermentation, and CO2 bags. The problem with these techniques is that while these alternatives are very affordable, they are crude, create small amounts of CO2, and display poor results.
Pro tip: To save on costs, turn off your CO2 generator about an hour before the grow lights turn off in your growing space. Plants don't use co2 at night as there is no light!
Pros and Cons of Using CO2 Enhancers
Bigger yields: it is proven that adding more CO2 to your grow area will result in faster growing plants, and bigger yields. Who doesn't want more cannabis for their hard work?
You plant will be able to tolerate higher temperatures: This is especially beneficial to those with hot, bright grow lights. When the CO2 concentration is above 1200 PPM, your plant will be able to tolerate temperatures up to 30C (86F).
Most effective with bright lights: If you have grow lights that aren't very bright, this method will not be as beneficial. This method works best when the plant is supplied with more light than it can use, as this is when your plant will be able to take in more light than it naturally would be able to.
Costly: This method can become costly, especially if you need to seal your growing area. You also have to purchase refills of CO2, so it is an added cost to every grow. However, it can be worth it if you get significantly larger yields!
Nowadays, more and more growers choose to cultivate their favourite strains indoors (for example super silver haze), as it is very rewarding to be able to grow cannabis year round, regardless of where you live in the world. However, many of these people are still missing the value of increased productivity that CO2 offers.
CO2 tank technique and generators offer an exciting avenue for growers to enjoy the staggering, proven benefits of carbon dioxide on plant growth.
While these techniques may be expensive to set up, growers can expect to realize quick returns on investment.