As you dive deeper into the hydroponic world, you will eventually happen upon hydroponic CO2. While most beginners overlook CO2 supplementation, studies show that it can increase yields by about 50%! The whole process may seem intimidating at first, but we’re here to walk you through it.

Read on to learn all there is to know about hydroponic CO2. By the end of this article you’ll be buying your own CO2 system right away!

What is CO2 and Why Should I Use It?

CO2 is an abbreviation for carbon dioxide. It stands for the fact that carbon dioxide has one carbon atom and two oxygen atoms. CO2 is used by plants in photosynthesis.

Because CO2 is so vital to photosynthesis, adding it to your grow room can create a massive increase in growth, leading to huge plants and healthy plants.

Thankfully, using CO2 is pretty easy once you know how. That’s what we’re here for!

How Does CO2 Benefit My Plants?

Plants can’t grow without CO2. While it’s naturally found in air, adding extra CO2 allows plants to photosynthesize even more. Photosynthesis is how plants produce energy and therefore is the powerhouse behind all plant growth and activity.

Keep in mind that outdoor air already has enough CO2 for the plant growth you’re looking for. CO2 is typically only added to grow tents or indoor operations.

How Much CO2 Should I Add?

In the hypothetical ideal environment, CO2 levels should be 1000 ppm. In reality, aiming for 800 ppm is a good bet.

Ppm stands for “parts per million” and, in this case, refers to how much CO2 is found in a million air molecules.

Hydroponic co2

How to supplement your grow with CO2

Introducing additional CO2 to your hydroponic system will proliferate growth, and it’s also very simple!

With a little know-how and a couple hours of time on your hands, you’ll have supplemental CO2 in no time.

Let’s talk about some options for CO2 enrichment methods.

Bottled CO2

Using bottled CO2 is the most popular way to introduce CO2 to your grow room. 

This method uses a CO2 tank, a pressure gauge, a flow meter, a valve, and a timer.

The pressure gauge lets you know how much gas is left in your tank. The flow meter tells you how much gas is being released. The valve lets you turn the tank on and off. Lastly, the timer can control the valve automatically.

CO2 Generators

For a long time, CO2 generators were reserved for commercial grows. Thankfully, hobbyists can now enjoy their benefits thanks to innovation leading to smaller, cheaper units.

CO2 generators burn natural gas or propane. A pilot light ignites the gas after a timer opens up a valve that releases the gas.

Adding CO2 using a generator is cheaper than using bottled CO2.

That being said, they can give off a lot of extra heat. Depending on the temperature requirements of your setup, this may be an issue.

More importantly, CO2 generators have the ability to produce a deadly gas called carbon monoxide if they’re not working correctly. It’s important to buy from reputable brands and check in on your generator often.

A blue flame indicates that your generator is producing CO2, while a yellow or orange flame indicates that something is wrong. Turn it off right away and don’t turn it back on until a professional fixes it.

Other Ways to Add CO2

There are plenty of other ways to add CO2 to your hydroponic garden, although it will be more difficult to control the exact CO2 levels being released. That being said, there is a low chance of adding too much CO2 with these less-common methods.

Decomposing Organic Matter

One way to increase CO2 is to add decomposing organic matter to your garden. Organic matter naturally releases CO2 as it decomposes. Leaves, manure, and hay are all good methods. 

However, using decomposing organic matter can get messy, smelly and brings the chance of disease and fungus.


Just like decomposing organic matter, the fermentation process naturally releases CO2. You can mix water, yeast, and sugar to cause fermentation.

Dry Ice

Dry ice is actually the solid form of CO2. It’s formed by compressing CO2 until it “freezes” into a solid. 

The cool thing about dry ice is that there is no “liquid” phase. That means the dry ice doesn’t melt into a liquid form- it goes straight into being CO2 as a gas.

Dry ice is a very expensive way to add CO2 to your garden, but awesome nonetheless.

CO2 Safety Measures and Precautions

Being exposed to too much carbon dioxide gas can be lethal. Safety needs to be your top priority when working with CO2.

CO2 is colorless and odorless, so you won’t know if too much is being released.

You should absolutely invest in a CO2 detector to monitor carbon dioxide levels. This way you can be alerted if too much CO2 is being released.


Time for the FAQ!

Is CO2 good for hydroponics?

CO2 is good for hydroponics. CO2 is one of the main components of photosynthesis. Photosynthesis is what gives plants energy, causing them to grow. Adding CO2 will improve plant growth and lead to higher yields.

How do you add CO2 to hydroponics?

You can add CO2 to hydroponics using: bottled CO2, CO2 generators, decomposing organic material, fermentation, or dry ice.

What should the CO2 be in a grow room?

The CO2 in a grow room should be about 800-1000 ppm. This level is safe for humans while also high enough to proliferate plant growth.

Can you give plants too much CO2?

You can give plants too much CO2. Too high of CO2 levels will push your plants too hard and they won’t grow as well.

How much will CO2 increase yield?

People make bold claims about how much CO2 will increase yield, but most studies show that CO2 will increase yield by around 50%.

Should I use CO2 in my grow room?

You should use CO2 in your grow room. CO2 is one of the main components of photosynthesis, and indoor grow rooms won’t have as much CO2 in the air as the outdoors naturally does. Therefore, adding CO2 will increase the rate of photosynthesis, driving more plant growth.

Do plants need CO2 at night?

Plants need CO2 at night, but they don’t necessarily need extra CO2. You add extra CO2 to your grow room in order to increase photosynthesis. Plants don’t undergo photosynthesis at night. That being said, your plants are constantly breathing air in and out through their stomata- so they are still intaking CO2 and releasing oxygen all night long.


Clearly, hydroponic CO2 is an incredible way to increase yields, speed up your plant growth rate, and generally make your plants happier in a short period of time. Once you’ve gotten a hang of hydroponic basics, adding CO2 supplementation to your setup is a great choice to make.

If you found this guide helpful, check out the rest of our how-to’s!