The Best CO2 Controller for Grow Room Reviews & Setup

If you're a cannabis grower, you want to have the finest cannabis plant in your garden with covered in tons of fat buds.

You also want to attain the highest yields in your grow room.

To achieve this, simply have the right levels of CO2 grow room kit!

Any plant that is grown indoors requires stringent conditions to ensure that it grows to give you many buds per plant.

Keep reading if you want to learn:

  • Why you want a CO2 controller in your grow room.
  • The different types of controllers and how much CO2 you need in your garden.
  • And the best CO2 controller for your grow room.

Quick Top 3 CO2 Controllers:

*Keep reading for the full grow room controller reviews

Why do you need a CO2 system for your grow room?

Humans inhale oxygen and exhale CO2.

Plants breathe CO2 and exhale oxygen.

It’s why plants and humans get along so well.

Over the evolution of cultivating marijuana indoors, growers have discovered boosting CO2 has direct effects on crop yields.

The atmosphere contains 400 ppm of CO2, but cannabis can take so much more than that.

Depending on the stage of growth, you can boost the CO2 in your grow room up to 1,000 to 1,500 ppm.

The additional CO2 makes your plants healthier and your final yield higher.

But, additional CO2 must be controlled for safety, for efficiency, and maximum yield.

How Much Does it Improve Crop Yield?

Accurately measuring how much CO2 will increase crop yields in cannabis, hasn’t been sufficiently studied (yet).

However, most growers report between 10 to 40 percent increases in the harvest.

There are so many variables it's impossible to predict how much you’ll get out of CO2 enrichment.

Your experience, soil, strain and fertilizer regiment will all have a say.

Most growers see benefits but fail to measure all the influences, so making accurate predictions difficult.

How to Make CO2 for plants

Before you can control the level of CO2 in your grow room, you must first design a system to produce it.

There is a range of option for the newbie at-home grower to the commercial producer.

These options range in price, output, technical skill required and safety.

The most common DIY options are:

  • Simply improving airflow in the space (depleted air out and fresh air in).
  • Yeast, the organisms naturally produce CO2 as they ferment.
  • CO2 canisters, when shaken slowly release CO2
  • CO2 pads and sheets.

Commercial options:

  • CO2 generators, which burn natural gas
  • Compressed CO2 tanks
  • Dry ice, which is solidified CO2

Keep reading for affordable ways to improve CO2 without investing in professional CO2 systems.

Why do I need to control the CO2 levels in my grow house?

Cannabis growing is fast moving from the secret closet growing to high tech farming on a massive scale.

Growing herb in your grow room brings with it Carbon dioxide (CO2) conditions that you have to meet to ensure the best yield from your crop.

So, adding CO2 to your grow room will, you guessed it, give you better yields and stronger, healthier plants.

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Carbon dioxide (CO2) is one of the most crucial requirements to the growth of any crop. Insufficient CO2 causes crops to stunt in growth or even die.

When growing cannabis in a grow room, it's importance you control the air in these spaces.

When growing cannabis in a grow room, it's important you control the air in these spaces

See: Cannabis Ventilation.

The maximum PPM (parts per million) of CO2 sufficient for cannabis growth is 1500ppm and anything above this becomes toxic to your crop.

How Much is Too Much CO2?

Injecting any gas into your indoor space may seem a bit unsafe for your health.

However, it would take some severe miscalculations to reach to levels of CO2 necessary to kill a person.

A lethal level of CO2 is 5,000ppm.

Thankfully, long before the CO2 levels got that high, you’d start to notice significant changes in your crop.

Marijuana plants only need between 1,000 to 1,300 ppm, maybe up to 1,500 ppm to thrive.

Anything over 1,500 and the CO2 will begin to stunt growth and affect the crops overall health.

It’s one of the many reasons why having a controller, mounted on the wall in the room, is such a pivotal part of the equation to boosting CO2 levels.

How Much is Not Enough?

If you don’t have a controller in the grow room, you may never know how much CO2 is still left in the atmosphere.

CO2 is one of the key elements cannabis needs to thrive, without enough the plants can effectively stop growing.

Perfect levels vary for different crops, but cannabis needs at the very minimum 200 ppm to survive.

As mentioned, the air we breathe inside contains roughly 400 ppm.

The more plants you have crammed into a space, the more CO2 they will suck out of the atmosphere.

Monitor the levels closely, to make sure the CO2 levels support optimum growth.

Do You Need to Adjust CO2 Levels During Different Marijuana Growth Stages?

Your cannabis crop doesn’t need peak CO2 throughout its entire lifecycle.

In fact, in the early stages, you’ll want to slowly introduce CO2 enrichment into the environment to avoid shocking the small seedlings or clones.

In the early stage, adding just 800 ppm of CO2 should be enough.

You can maintain this relatively low level of enrichment throughout the vegetative stage.

As the plant matures, and you want to encourage it to focus on bud development, CO2 becomes a handy tool.

Increase the levels of CO2 during the flowering stage to roughly 1,200 to 1,400 ppm.

How to Use a CO2 Controller

There are technical controllers and controllers for dummies.

The technical ones, for large-scale commercial grow ops, may even require a professional to install.

However, most controllers for the at-home grower, have a very user-friendly setup.

Depending on the strain, stage, and light schedule, you’ll need to adjust the levels and timing of the CO2 release.

Some models don’t even require calibration, they are a set-it and forget-it type system.

The perfect system for the grower who has no technical skills, and doesn’t want to mess around.

How to Set up a Controller

When you receive your CO2 Controller, you’ll want to review all the instructions carefully.

Not all controllers were created equal, and the set up from one to another will vary significantly.

You’ll need to mount the controller to a wall within the grow room, preferably at the height of your plants.

Setting it at the same height as a mature cannabis plant will hopefully capture the CO2 levels the leaves are getting exposed to.

Next, explore the resettings, if the product has them, or set a few yourself.

Think about the stages of growth, and the different needs your plants will have throughout the cycle.

Finally, set it and let it monitor your grow.

The Best CO2 Controller for Grow Room

CO2 Meter RAD-050 CO2 Monitor

Day and Night CO2 Monitor and Controller for Greenhouses

This CO2 controller is relatively inexpensive and exceptionally easy to use giving it the title of the best grow room controller.

Its accuracy is unmatched by other controllers of its level.

It has a photo sensor that switches off the CO2 supply when there is darkness because CO2 is only useful to your plants during the day.

The downside of this controller is that it has a one-way relay, which means that you need to have more than one if your space is big.

The space limitation is 1500 square feet.

Anything above this size means that you will need additional controlling equipment.

Titan controls 702618 Atlas 2

Titan Controls HGC702618 Professional Series Atlas 2-Preset CO2...

This controller is the easiest for you to use and consumes very little energy.

It just requires plugging in!

It features a steel casing that provides protection for your equipment and ensures a long life.

Just like the CO2 Meter RAD-0501, it also has an in-built photo sensor to help you control the CO2 levels only during the day and saves power at night.

Its only downsides are that it might be a bit expensive and its calibration is limited due to the inbuilt calibrator that makes it difficult to adjust beyond a certain point.

Titan Controls 702608 Atlas 3

Titan Controls 702608 Controller

This is the most efficient controller you can get on the market presently.

You just need to connect it to your generator, plug it in, and it does the rest for you.

It comes in a plastic casing that makes it resistant to moisture and dust.

This implies that it's highly protected guaranteeing longer useful for you.

It also calibrates itself such that you do not have to keep readjusting.

The manufacturer has a guaranteed warranty of up to 3 years.

This convenience, however, comes at a cost that might make it unattractive for those operating on a constrained budget.

Just like the Titan 2, you can have difficulties recalibrating due to the built-in feature of self-calibration, which can make it difficult to adjust.

How much does CO2 cost?

You can add a bit of CO2 free, or invest in a professional CO2 system for thousands of dollars.

Technically the more time you spend in the grow room, the more CO2 you exhale.

Effectively improving the CO2 in the room, for no money at all.

There are, of course, other affordable and more effective ways to boost CO2 levels.

CO2 exhaling bags range in price depending on output but typically cost under $40.

A CO2 Pad, which releases a slow supply of CO2, is even more affordable.

A compressed CO2 tank system requires more upfront investment in the tank, regulator, hoses, and timer.

This more professional system is better over the long run.

Together, these items can cost a few hundred dollars.

How to Save Money on CO2 Enrichment for Cannabis

Just like you wouldn't want to cut costs on a carbon filter--and would instead opt for one of the top ones found here--you shouldn't short change the CO2 controller.

First things first, purchase a CO2 regulator.

This handy little device will allow you, the grower, full control over the process.

Set the device to manage the perfect levels of CO2 in your grow room atmosphere.

No need to waste valuable CO2 if your plants don’t need it.

Second, seal the grow room up to avoid costly leaks of CO2 into the outside world.

Third, turn the CO2 off at night.

Most controllers should come preset with this dark mode because cannabis doesn’t need any CO2 during the dark cycles.

The Importance of Grow Room Setup for CO2 Enrichment

It’s all well and good to add some CO2 into your grow room, but if it escapes you are just wasting your money.

The importance of sealing the grow room from outside and from any unregulated airflow is just as critical as sealing the grow from outside light sources.

You’ll also want to set up the fans, ventilation, and other tools managing air flow so that it doesn’t just blow the CO2 away from your plants.

Instead, work on a system which circulates the CO2 throughout the grow.

How to make a Homemade CO2 Generator

You can, of course, buy an all-in-one system to release and regulate your CO2 for you.

But you can also make one yourself.

The items you need for the most professional set up include:

  • Compressed CO2 Tank
  • Pressure regulator
  • Solenoid valve
  • CO2 Controller
  • Hoses

While this setup requires a bit of investment in terms of upfront costs, over time it pays off.

A single tank of compressed CO2, available from a welding supply shop, will last for growing after grow before needing a refill.

It also gives you control over how much, and when, the CO2 is released.

How to Setup CO2 in the Grow Room

Here we will cover the basic steps of how to set up pressurized CO2 tanks in the grow room.

The simplest CO2 options such as the all-in-one bag or bottles are too easy to need directions.

  1. Set up the Controller: Usually they come preset, and already scheduled to turn off during dark periods - adjust if needed (don’t forget to a fix to the wall).
  2. Connect Regulator to Tank: One end of the regulator should connect to the CO2 tank, and the other to flexible hosing.
  3. Poke Holes Throughout the House: Small holes along the length of the hose will allow CO2 to permeate your room.
  4. Place Hose: Most experts suggest placing the hose above your plants, so the heavy CO2 sinks through the leaves to the floor.

If you are having trouble with your humidity levels too, check out our guide on the best humidifier for your grow room.

Learn from the Experts on CO2 Compressed Air Set Up

CO2 compressed tanks, may need a bit of technical know how to properly set up.

Which is why, if you don’t have an expert on hand to help you, you’ll want to find one online.

MycoHeadGROWER, gives a full break down of his compressed CO2 system.

Including why he decided to choose the set up he did, and what components it requires.

It’s a good class on CO2 101, perfect for anyone getting serious about adding a bit of CO2 into their own grow room.

A Cheaper DIY Option for Home Growers

Okay, so maybe you’ve just got a few plants, and you don’t want to do a full compression tank set up.

The investment of a few hundred dollars isn’t affordable or necessary for all levels of weed cultivation.

The good news for growers on a budget is there are many super-cheap options to boost the CO2 for your plants.

One easy way to add CO2 is with a fermentation bucket, using yeast and sugars.

As the yeast consumes the sugars, the little living organisms burp out CO2.

The system replicates the fermentation process of wine and beer making.

Using CO2 Bags for a Grow Tent

Another option for small spaces, like a grow tent, is to purchase a quick, easy to set up product, like a CO2 bag.

CO2 bags look like a small sacks of soil, but inside the compounds are working hard to produce CO2.

This is usually a natural process; fermentation, or fungi, which pump out high levels of CO2.

If you are growing in a small space, these a CO2 bag is a safe and straightforward solution.

All without the need for heavy and expensive compressed tanks or CO2 generators.

A CO2 bag, usually under 30 dollars, will pump out continuous CO2 for up to six months.

One bag is usually sufficient for upwards of six plants.

Another Cheap Option: A DIY CO2 Bag

Make an at home CO2 Bag with the following items:

  • Cut up pieces of cardboard
  • Cut up button mushrooms
  • 2 tbsp white sugar
  • Old coffee grounds
  • Water
  • Big freezer bag
  • Empty water bottle

Step by step instructions:

  1. Add the first five ingredients together in a bowl, and mix well. It’s going to get messy but go with it.
  2. Once combined, add the mixture to the big freezer bag.
  3. Take the empty water bottle and cut off the screw top (both bottle and cap portion).
  4. Poke five to six holes into the cap.
  5. Place the bottle side inside the bag, and the cap on the outside, screw the parts together, trapping the bag in between.
  6. Poke holes through the cap into the bag to provide ventilation.
  7. Tie the bag shut.

Signs that Your CO2 Enrichment is Working

Improving the CO2 levels in your grow room effectively improves the process of photosynthesis. The more light the plants process, the faster and bigger they are able to grow.

Essentially, with CO2 comes increased chlorophyll production.There is also an improved root-shoot ratio. This means there is less focus on root development, and a higher focus on growth (leaf) development.

As you can imagine, this root-shoot ratio is crucial in cannabis. In the vegetative stage, it refocuses the plant's attention from its roots to ‘shoots’ or its foliage.

Signs that Your CO2 Enrichment is Failing

If your CO2 enrichment isn’t working, your plants are getting too much or too little CO2.

Too much CO2, and you’ll start to see visible damage on the leaves, shoots, and buds.

Too little CO2 and your plants will stop growing altogether.

One day you’ll enter into the grow room, and you’ll realize that you haven’t seen much growth over the last week.

No growth is a telltale sign that your plants have sucked all the valuable CO2 from their environment, and you need to add more.

With a CO2 controller, of course, you don’t need to play the guessing game about CO2 levels.

It’s readily and easily displayed.


Most of our grow rooms don't need a controller just like most don't need buy one of the grow room ac units here.

After all, most of us just grow in a 4x4 grow tent where hooking up a small homemade CO2 generator running every once in awhile will be enough.

But, if you want to take your plants quality to the next level you need to start monitoring your grow rooms CO2 levels.

And for that, you need the best CO2 Controller for grow rooms. 

Be sure that you also check out our guide on grow tent reviews to make sure your CO2 isn't being wasted by using a bad tent.

Last update on 2021-03-25 / Affiliate links / Images from Amazon Product Advertising API

1 thought on “The Best CO2 Controller for Grow Room Reviews & Setup”

  1. My question is this, if you are setting up a CO2 generator for a 1500 sq ft grow room, do you still want to setup an exhaust system for fresh air exchange? My first thought is that during “lights on” you don’t need or want the exhaust running, all your doing is sucking out the CO2 you are adding. However, during “lights off” you want exhaust running to remove the toxins the plants are purging from their system. This would mean a timer on both the generator as well as the exhaust system.



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