If you're growing plants indoors—especially in a sealed tent or grow room—adding carbon dioxide (CO₂) can be one of the most effective ways to supercharge your yield. But with so many options out there, from ExHale CO₂ bags to full tank-and-controller systems, how do you choose the right method?
Let’s dive into what CO₂ does for plants, and then break down the pros and cons of CO₂ bags vs. CO₂ tanks.
🌿 Why Do Plants Need CO₂?
Plants use CO₂ in photosynthesis—the process of converting light, water, and carbon dioxide into sugars (energy) and oxygen. The simplified equation looks like this:
More available CO₂ (within limits) means plants can photosynthesize faster, resulting in:
-
Faster vegetative growth
-
Bigger leaves and stronger stems
-
Higher yields and heavier harvests
-
Greater tolerance to heat and environmental stress
In a natural outdoor setting, plants have access to the atmosphere’s ~400 ppm CO₂ level. But in a closed indoor grow, that CO₂ gets used up quickly—and if it's not replenished, growth slows or even stops. That’s where CO₂ supplementation comes in.
🛍️ What Are CO₂ Bags?
CO₂ bags, like those made by ExHale or TNB Naturals, are a low-cost, low-effort solution. These bags contain mycelium (fungal culture) or a chemical mix that slowly releases CO₂ as a byproduct of biological activity.
How they work:
-
You hang the bag above your canopy or place it near your plants.
-
CO₂, which is heavier than air, gently "falls" over your plants.
-
No electricity, no equipment, no maintenance.
Pros:
-
Super easy to use
-
No setup or tools needed
-
Great for small tents (2x2 to 4x4 ft)
-
Lasts 3–6 months
Cons:
-
CO₂ output is inconsistent
-
No ability to turn off/on or control ppm
-
Not suitable for large or highly-optimized grow rooms
🧯 What About CO₂ Tanks?
CO₂ tanks are a more advanced and precise option, commonly used by serious growers or commercial setups. A typical system includes:
-
A compressed CO₂ tank
-
A regulator with a solenoid valve
-
A CO₂ controller or timer
With this setup, you can dial in exact CO₂ levels—usually between 1,000 and 1,200 ppm—for optimal plant performance.
Pros:
-
Fully controllable and consistent CO₂ levels
-
Scalable to larger grow rooms
-
Ideal for use with high light intensity (HPS or LED)
Cons:
-
Higher initial cost ($200–500+)
-
Requires calibration and ongoing tank refills
-
More complex installation
📊 Side-by-Side Comparison: CO₂ Bags vs. CO₂ Tanks
| Feature | CO₂ Bags | CO₂ Tanks + Controller |
|---|---|---|
| Cost | 💲 Low ($20–40) | 💸 High ($200–500+) |
| Ease of Use | ✅ Very simple | ⚠️ Requires setup and monitoring |
| Output Consistency | ❌ Variable | ✅ Precisely adjustable |
| Control | ❌ None | ✅ Full control (via timer/sensor) |
| Lifespan | ~3–6 months (one-time use) | Ongoing with refills |
| Best for | Small grows, hobbyists | Medium–large grows, pros |
| Maintenance | Minimal | Moderate (refills, calibration) |
🧠 Which One Should You Use?
Choose CO₂ bags if:
-
You’re a beginner or casual grower
-
You’re working in a small tent or closet grow
-
You want something cheap and maintenance-free
Choose CO₂ tanks if:
-
You’re growing in a sealed room or large tent
-
You’re running strong lighting and high-performance setups
-
You want full control over your grow environment
🌱 Final Thoughts
CO₂ is one of the most overlooked ways to maximize indoor plant performance. Whether you choose a simple bag or invest in a full tank system depends on your goals, budget, and grow space size. For many home growers, a CO₂ bag is a great place to start. But if you're chasing big yields and have the environment to support it, tanks and controllers give you the control you need to push plants to their full potential.
Need help picking the right CO₂ system for your grow room? Reach out—we’re happy to help you grow smarter.