Best Way of Adding Co2 to Tent Grow ( An Ultimate Guide)

(Last Updated On: May 21, 2021)

You’re caught in between the devil and the deep blue sea. You can’t make a clear-cut decision on how to add CO2 to your grow tent, right?

Well, it’s quite understandable, and you’ve got no reason to freak. We’ve all been caught in between a rock and a hard place. And, it’s easy to get confused when deciding on how to introduce CO2 to our cannabis plants growing indoors.

Growing cannabis indoors is never a walk in the park. You’ll always be on the lookout for new and innovative ways to make your plants grow healthier and stronger, and to maximize your yields.

Glad you found this article, as I’m going to teach you the best way you can add CO2 to your grow tent. But before then, let’s learn what CO2 is and how it benefits your plants.

What is CO2, and Why Do Plants Need It?

Carbon dioxide (abbreviated as CO2) is a colorless, odorless gas that’s naturally found in the atmosphere. We, human beings, exhale this gas when breathing out while plants like cannabis use it for photosynthesis.

So, why do plants need CO2? And How Crucial Is It?

Like I said, CO2 is important for the processes of photosynthesis to take place. Okay, listen, photosynthesis is a process that plants use to convert light into energy to facilitate growth.

Here’s an equation representing how photosynthesis occurs:

CO2 + H2O + light = photosynthesis

As you can see, three things must be available for this process to complete successfully, including CO2, H2O (water), and light.

Now, what’s ringing in your mind? You’re right; no growth would occur if one of these components is missing, and plants would eventually die.

That means if you fine-tune your indoor growing system correctly and supply the right amount of carbon dioxide, water, and light, your plants will grow faster and healthier, resulting in boosted yields.

How Much CO2 Do Plants Need?

As much as CO2 is fundamental for plant growth, you must supply it in the right amount. If you add sufficient amount of CO2 to your grow tent, your plants will develop bigger, dark green leaves, and more fruits and flowers.

CO2 levels are measured in parts per million (PPM). So, how much CO2 in PPM do plants need for healthier growth?

Naturally, there’s only around 400-450PPM in the air. It can be as high as 800PPM in homes due to heavy exhaling of CO2 by human beings.

Anyways, plants like cannabis grow best at around 1200PPM. And the natural atmosphere falls short of this optimum PPM.

Now, let’s make a quick twist and go back to our main subject of convo: how to add CO2 to grow tent.

We’ll strike it up right away…

Best Way of Adding Co2 to Tent Grow

There’re three common ways of injecting CO2 into a indoor grow tent. These include using CO2 bags, Liquid Propane Gas (LPG), and Bottled CO2 Gas. Before you opt for any given method, you must consider the size of your grow room, your budget, and how much CO2 you need to inject.

CO2 Bags

This slow-release approach is ideal for indoor gardeners who need the easiest and budget friendly method of adding CO2 to tent grow. Most generic CO2 bags cost under $20, while the top rated Exhale 365 Self-Activated CO2 Bag retails at under $40.

The reason I like this bag is that it has a “self-activated” design, which makes it easy to use. All you gotta do is remove a retaining clip to enable mycelium spores to drizzle into the sterilized substrate in the bag.

Then, hang it slightly above your plant’s canopy, and turn your fans on to circulate around it. If you’re using a 4’ X 4’ grow tent, the Exhale bags can raise CO2 levels from 400PPM to 1350PPM. This is pretty awesome for people on a budget.


  • Low cost
  • Natural release
  • No running costs
  • No excess humidity or heat


  • Bags can form a shadow if not positioned correctly
  • May take weeks to activate and produce CO2

Bottled CO2 Gas (Compressed CO2 or CO2 Tanks)

This CO2 generation method is a tad complicated but still affords brilliants results every time. It’s best if you got a small budget and want to step up from using CO2 bags.

Equipment You Need

Often, compressed CO2 comes in pressurized metal containers. You can get them from most welding supply stores, gardening stores, or hydroponic stores.

With this way of adding CO2 to grow tent, the initial investment in equipment can be high. Nevertheless, the cost of refilling your CO2 tanks is cheaper in the long run.

Furthermore, a single bottle or tank of compressed CO2 can last several grows. It’s easy to keep the CO2 levels in check if you’ve got an automatic CO2 PPM Monitoring System.

However, if a regulator and timer are all you have, then you’ll need to add CO2 to your grow room for small periods of time –with the lights on – using a timer.

I recommend measuring and adjusting the PPM over time until you’ve mastered how to maintain the 1200-1500 PPM range.

The best CO2 tanks can be linked to a meter (CO2 PPM Meter) for measuring the level of CO2 in the air. A meter also allows you to adjust your CO2 output as you need.

A 1200-1500 PPM range is adequate for cannabis plant growth. If you’ve got a meter attached to your CO2 tank, you’ll be able to automatically inject more CO2 into the air above your plant’s canopy when CO2 levels plunge below the optimum. This ensures an automated system.


  • Very effective
  • Provides full control over PPM using a regulator or controller
  • Can be automated using a controller
  • Lower cost in the long run
  • Precipitates CO2 when you need it


  • Higher initial cost
  • Tanks can explode if exposed to an open flame

CO2 Generators (Liquid Propane Gas)

This is where a CO2 generator burns liquid propane gas to release carbon dioxide. A chemical reaction which results from burning propane leads to production of CO2 and water vapor.

Just like CO2 tanks, CO2 generators are costly and vary in coverage. A smaller 4 kWAutoPilot Generator can cover up to 30 square meters while a bigger 10kW Pro-Leaf LPG Generator can cover up to 220 square meters.

This method of injecting CO2 into a grow tent is befitting for closed-loop rooms or spaces with air-cooled lights.

Equipment You Need

  • LPG Generator (such as AutoPilot or Pro-Leaf)
  • Red/orange propane canister
  • Pipe cutters
  • Propane regulator (with low pressure)
  • Leak detection fluid
  • Gas hose clips
  • CO2 controller (with sensor/analyzer)

If you’re going to use A CO2 generator in a small grow tent, make sure to keep monitoring the temperature from time to time.

Note that CO2 generators give off both CO2 and heat. Therefore, they may end up causing a significant increase in temperature.


  • Propane gas is easily available in most garages
  • Lower operational cost than bottled CO2
  • Easy to use with a controller
  • Precipitates CO2 when the need arises


  • Initial cost is higher (CO2 generators are expensive)
  • Releases moisture as a by-product, which is not great for flowering

Final Words

Up to this point, I believe you’ve now chosen your best way of adding CO2 to your grow tent. As far as I am concerned, I think using CO2 bags is an easier and cheaper way to add a bit of CO2 mist to your grow tent.

With CO2 bags, you’ll be able to cultivate CO2 gas naturally 24 hours a day, and without having to refill bottles or use expensive production units. Anyways, the decision on how to add CO2 to your grow tent ultimately lies with you. Just choose what you deem is right for your indoor cannabis growing needs.

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