CO2: the benefits of adding carbon dioxide to your grow

Why use Co2 in my grow?

There are two main benefits to using Co2 in your indoor garden that I found: greater yield and faster growing. To explain further, plants have a certain amount of moisture and energy in their leaves at all times, and Co2 aids in bringing out that energy to help your plants thrive. By unlocking that stored energy, most growers agree that you will get about 20-30% more yield with an increased growing speed of at least 15%.

What is Carbon Dioxide (CO2)?

Plants breathe differently than humans and other animals. While animals breathe in O2 and breathe out carbon dioxide (CO2) plants do the reverse. This is one of the most important factors why plant life is an essential part of Earth's ecosystem. Without greens, CO2 levels would reach suffocating levels in an extremely short while. CO2 is used by plants for growth, because it's essential for photosynthesis, alongside light and water.

Even though the current CO2 levels in the atmosphere is about 350 PPM, it seems that plants have maintained their ability to consume up to 1500 PPM of CO2, as they did eons ago. Knowing this is extremely important because the assertion that plant growth could be sped up by increasing the CO2 intake is true.

What do I need to know before adding Co2 to my grow?

CO2 regulator

Co2 will increase the humidity of your grow, which in turn creates more moisture. More moisture you have in your grow means the potential for fungus and rot in your garden increases. Moreover, if you let your Co2 go unregulated it can create a toxic environment for your plants and yourself. A Co2 level of over 2000ppm can kill your plants, and levels higher than that can become unsafe for humans and animals to breathe.

Keep in mind that a quantity below 250 PPM of CO2 will harm your plants. Let's say you have six plants growing in your dressing and there is no artificial or natural ventilation provided. In this case, your plants will use all available CO2 in a few hours. When the CO2 supply is exhausted, the plants will stop growing. This is one of the reasons why you must provide ventilation and fresh air for your plants constantly.

To avoid these issues you’ll need to control ppm levels by venting your grow. Most use meters to measure the levels of Co2, like the LTL Co2 Air Controller we offer. For venting, you’ll need fans and ducting. Some use duct fans that connect to aluminum ducting and escapes through exhaust ports on your tent. Others use in-line fans that connect directly into the ducting and carry that out of your garden via exhaust ports in your garden.

Now, Co2 is heavier than oxygen so it usually falls down a lot easier than oxygen. But when venting your grow, there is a potential for the abundant natural oxygen in your growing area to overpower the Co2 and render it useless. On the flip side, if there is too much Co2 in your grow the humidity levels will get too high and prevent the plants from growing.

Because you’re giving your plants more Co2 to increase the speed for your grow, you will need to keep a close eye on your garden as you will need to compensate the extra Co2 with more water, nutrients, and light. This increase in energy will mean higher temperatures in your grow. Venting should be done in a closed area and done only when your lights are off to lower the temperature of your grow.

For example, when using HID bulbs (like HPS and MH bulbs in your grow light system), you’ll want to vent your area to cool your grow because HID’s emit so much energy and heat. When using LED’s, on the other hand, you won’t have to worry so much about the heat, but you will always want to vent your growing area to regulate the ppm level.

What does Carbon Dioxide do for your plants?

CO2, when done right, will increase the speed and yield of your grow. With that speed, you’ll have more harvests per year, and in turn, you’ll have bigger and better yields without having to go through a dry period.

When a grow can utilize Co2, you'll increase the moisture content in your grow and give your plants more resiliency. Plants can usually only survive in 70-degree temperatures, so with Co2 plants won’t dry out as easily when maintained. That means your plants will be able to take a little more heat than it usually would and your plants will be better for it.

To provide a supplement of CO2 to your indoor farm you can use a CO2 regulator attached to a can of CO2 or a CO2 generator. These growing options will help your plants grow optimally. Researchers proved that an increase in growth rates by up to 20% and an up to 30% increase in size can be achieved by increasing and maintaining CO2 levels to over 1 200 PPM. Remember that levels above 1 500 PPM are toxic and plants will tend to have a very stringy growth.

Using CO2 in Your Grow Room

As we've mentioned, CO2 is heavier than oxygen so keep in mind that CO2 will need to essentially "rain" down on to your plants. That said, there are 3 main ways to introduce Co2 into your grow: a regulated tank of Co2 (regulated by a device such as our Co2 Regulator), a natural source of Co2, found in products like our EZ-Co2 Bag, or propane/natural gas burners.

Natural CO2 Generators

Using natural CO2 like EZ CO2 bags or DIY CO2 generators (like a bubbler in one bottle of water creating and sending CO2 to another bottle for use) is great for smaller grows. All you do is hang the device you want to use above your plants and let the CO2 naturally fall on to your plants.

These sources of CO2 don't offer lots of coverage, though. These sources are sort of like cool hood reflectors: great for providing plants directly below it the best power it can, but they're not known for their coverage. These are recommended for smaller grow rooms, like grow tents and closets. If you choose to use them in larger growing spaces, be sure to stock up- you'll need quite a few.

Regulated CO2 Tank

If you opt for this, know that you can get canned CO2 at most hydroponic stores. Keep in mind, however, that you'll need a CO2 regulator to create a constant flow of CO2 out of the tank. All you have to do is set the desired flow rate (measured in CFH) and set the timer to up the CO2 levels to your desired level. You'll have to do some math to set your CO2 levels just right, or you could opt for a CO2 PPM controller to maintain the wanted levels.

What's great about tanks is that depending on their size and your regulator, you can walk around your grow and fill your entire grow room with CO2 by hand. These are great for people with larger grow rooms who'd rather supplement carbon dioxide in their grow manually or semi-manually with a tank or two. They're also a little safer to use than CO2 generators and burners.

Propane/Natural Gas Burners

CO2 generators are specialized burners (they can be propane or natural gas based). The byproducts of this process are CO2 and water (humidity). So it's good to keep an eye out on the humidity levels in your growth op. These generators are usually optimized to produce as little heat as possible and at the same time to produce as much CO2 as possible.

Their capacity is rated in cubic feet per hour (CFH). A standard 10-by-10-by-8-foot room with a normal 350 PPM of CO2 density takes around one CFH to have its level raised to 1,500 PPM. Don't worry, the level drops throughout the day as the plants steadily metabolize CO2. To keep the levels constant smaller, controlled burners are required. A CO2 PPM regulator is perfect for keeping constant levels of CO2 inside the greenhouse throughout the day without you doing a thing.

Here are some that our store offers:

The Gro1 CO2 Regulator at $99.95

EZ CO2 Homegrown CO2 at $32.95

Applying CO2 in Your Grow Room

Since there won't be a natural abundance of it in your grow room you can supplement carbon dioxide in your garden. If you're ready to use it, start by getting a meter that will read the PPM content of CO2 in your grow room's environment.

Keeping CO2 levels around 1200-1500 PPM is ideal, but with higher CO2 levels in the environment, you'll want to keep your temperatures higher. Keeping your temperatures in the mid-'70s (21°C) to low 80's (26°C) won't do too much because your plants need the ability to take in, process, and expel what it's taking in. With higher temperatures in your grow room, your garden's metabolism can work at a pace that allows each plant to grow quickly and efficiently. Don't be surprised if your plants need temperatures around 85-95°F (29-35°C) for them to process light and nutrients properly.

(Note: Keep in mind that smaller grow rooms won't need- and can't use- such high CO2 levels, and therefore need to be adjusted. Further, the lower the PPM the lower the average-to-max temperature range will be)

How you give your garden CO2 will determine how simple it will be to regulate:

CO2 burners can be set to replenish levels when they're off, so when levels are too high all you have to do is open a window, open a vent, or turn on a duct fan and pull the air out.

If you walk around with a CO2 tank you'll need to keep an eye out on your meter and make sure you give out CO2 when levels are low. When you spray a little too much, just turn on a fan or open a vent and you'll be fine.

When it comes to CO2 bags, be careful not to waste CO2. You'll need fans to constantly run, but if your bags aren't putting out lots of CO2 you run the risk of pulling out CO2 before it gets the chance to hit your plants. In these cases, make sure you use small blade fans in the bottom corner of your growing space to make sure CO2 stays in the air.

Remember: you want to regulate Co2 in your grow in a way that maximizes your Co2 power without sacrificing the oxygen your plants need- and vice versa. Overall, Co2 will get you bigger, better yield and more yields per year. Keep in mind that Co2 can be a little tricky to add to your grow. You’ll want to be sure that your ppm level is at 1000-1500 by venting your system, and at the same time, you’ll want to keep up with your water and light levels at all times.

CO2 in a supply closet


Rod Feller

Thank you for the well written information. I highly suggest using Co2 as well i have had many successfully plants using the benefits of oxygen. It is a great read and for growers out there who do not use it i would say try it out for yourselves.

kyle johnson

This article has taught me a lot about carbon dioxide. It was interesting to learn that carbon dioxide can help you to ensure that your plants grow at a fast pace. I hope this article can help us to avoid oxygen deprivation for our plants.

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