Welcome to Happy Hydro's CO2 Flow Rate Calculator! 

Tailored for cannabis growers and indoor gardeners, this tool helps you quickly find the perfect CO2 flow rate for your grow room. Just enter the room dimensions and desired CO2 levels, and let our calculator do the work.

Disclaimer: This calculator is an estimation and should not be relied upon for commercial use.

CO2 Flow Rate Calculator

Version 1.0 - Created 8/24/23

How to Use the CO2 Calculator

  1. Enter Room Dimensions: Provide the length, width, and height of your grow room in feet.
  2. Input Ambient CO2 Level: The default value is 300 ppm. Adjust if needed.
  3. Set Target CO2 Level: Choose the desired CO2 level for your plants, such as 1120 ppm.
  4. Select On Time: Indicate how many minutes per hour the CO2 will be on.
  5. Click 'Calculate': Get the CO2 flow rate in cubic feet per hour (SCFH) instantly.

How to Add CO2 to Grow Rooms

Natural Sources

Utilizing natural sources like fermentation and composting is an eco-friendly way to introduce CO2 into your grow space. These methods rely on biological processes to produce CO2 and require careful management.

CO2 Generators

CO2 generators burn fossil fuels to produce CO2, offering a reliable and controlled supply. They are suitable for larger grow rooms where precise CO2 levels are required.

CO2 Tanks and Cylinders

Bottled CO2 provides a convenient and portable solution. Available in various sizes, CO2 tanks allow for easy control and adjustment of CO2 levels. When using equipment like this you will definitely want to use a Co2 calculator for your grow room.


When choosing a CO2 source, consider factors like safety, cost, efficiency, and compatibility with your grow room size and plant types.

Setting Up a CO2 System

Selecting the proper controller, CO2 regulator, and tank is crucial for an effective CO2 system. Controllers monitor CO2 levels, regulators control the flow, and tanks store the CO2.


Installation Process

  1. Connect the regulator to the tank.
  2. Set up the controller in a central location.
  3. Run tubing from the regulator to distribute CO2.
  4. Test the system to ensure proper functioning.

Connection with Fans

A fan pointed at the end of the tubing circulates the CO2 effectively, maximizing benefits to the plants.

Day/Night Considerations

Never run CO2 during dark periods. Use a timer to synchronize CO2 supply with the lighting schedule.

Tips for Calculating Ideal CO2 Levels

Starting Point

Experts recommend starting at 1,000ppm and adjusting over time. Avoid levels below 400ppm and above 1,500ppm, as they may hinder growth.


Importance of Other Factors

Enhanced CO2 levels must be complemented by proper soil, nutrients, watering, light, and cleanliness for optimum results.


Circulation Techniques

Utilize tubing with pinholes around the top of the grow room to allow CO2 to "drop" on the plants, as CO2 is heavier than air.


Temperature Considerations

Be mindful of temperatures above 27°C (80°F), as they may result in elongated stems and lower yields.

Frequently Asked Questions (FAQ)


Should I Consider Adding CO₂ to My Grow Room?

While adding CO2 is not a mandatory step, it can significantly enhance plant yield if you're looking to further optimize growth conditions. CO2 supplementation can be a valuable addition once other growth factors, such as nutrients and lighting, are well-managed.


What Is the Ideal CO₂ Concentration for My Plants?

The best CO2 concentration for most plants ranges between 1200 and 1500 ppm. However, it's crucial to balance CO2 with other growth essentials like nutrients, water, and sufficient light to see a positive impact on growth.


Can Excessive CO₂ Be Harmful to My Plants?

Yes, excessive CO2 can be detrimental to your plants for several reasons:


  • If there's insufficient light, added CO2 won't enhance growth.
  • CO2 levels exceeding 1500 ppm can be toxic and cause plant damage.
  • Avoid adding CO2 at night when photosynthesis is inactive, as it's unnecessary and wasteful.

How Can I Determine the Right Amount of CO₂ for My 70 Cubic Feet Grow Room?

The required CO2 volume for a 70 cubic feet grow room would typically be around 0.05-0.07 cubic feet or 1.5-2 liters. However, the exact amount depends on factors like the existing and desired CO2 levels. Use our calculator for percise results.


How Can I Ensure Efficient CO2 Distribution in My Grow Room?

Effective distribution can be achieved through proper circulation using fans and specialized tubing. Consider CO2's heavier nature and design the distribution so that it "drops" onto the plants. Also, align CO2 supplementation with the lighting schedule to avoid unnecessary usage during dark periods.


Is It Safe to Experiment with Different CO2 Levels?

Yes, experimentation can help find the perfect balance for your specific plants. Start with a recommended level around 1000 ppm, and gradually adjust, observing how your plants respond. Remember to keep CO2 levels within a safe range and maintain other growth factors for optimal results.

Support & Resources:

Need further assistance or have questions about using the calculator? Feel free to contact our support team or explore our extensive library of resources on cannabis cultivation. From beginner guides to advanced cultivation techniques, Happy Hydro is your go-to destination for all things gardening.

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