What does this calculator do?
It estimates how many pounds of CO₂ you need to raise the grow room from a chosen “ambient” CO₂ concentration (in ppm) to a “desired” CO₂ level. This is a basic calculation and doesn’t account for ongoing ventilation, air exchange, leakage, or plant usage. In practice, you’ll likely introduce CO₂ gradually over time and periodically refresh it due to exhaust fans or natural leaks.
CO₂ Usage Calculator
Estimate how many pounds of CO₂ you need to raise your grow room to a desired ppm, assuming the room is sealed and there's no significant air exchange.
*This calculation assumes standard atmospheric conditions and no ongoing ventilation. In real grows, continuous or repeated supplementation is necessary to maintain the desired CO₂ level.
What is this calculator estimating?
This calculator determines how many pounds (and grams) of CO₂ are needed to raise your grow room from an ambient CO₂ level (often around 400 ppm) to a desired level (e.g., 1,200–1,500 ppm). It assumes the room is sealed and does not account for ongoing ventilation losses, leakage, or CO₂ consumption by plants over time.
Why does the calculator assume no significant air exchange?
To simplify the math, we calculate how much CO₂ you’d need just once if the room were perfectly sealed. In reality, fans, exhaust systems, or even small leaks will lower CO₂ levels over time. You’ll typically introduce CO₂ continuously or on a timed schedule to maintain your target ppm.
Pro Tip: If you have active ventilation, consider using a CO₂ controller that monitors and regulates levels automatically.
How do I know what CO₂ level is optimal for my grow?
Many growers aim for 1,000–1,500 ppm during the light cycle to boost plant photosynthesis. However, more CO₂ isn’t always better; levels over ~1,600 ppm can stress plants or waste resources. Some growers find 1,200–1,400 ppm ideal for most strains.
Next Steps: Our cultivation courses at SativaUniversity.com/courses cover the pros and cons of different CO₂ levels.
What about safety concerns with CO₂?
High CO₂ levels can be dangerous for humans or pets. Growers should monitor CO₂ in enclosed spaces and ensure they have adequate ventilation and safety measures. Keep grow rooms away from living areas if you’re using tanks or burners.
Safety Note: Always follow local regulations and consider installing a CO₂ alarm for peace of mind.
How often will I need to refill my CO₂ tank or generator?
It depends on room size, desired ppm, leakage, and duration of supplementation per day. For example, a small, well-sealed grow might only need a refill every few weeks, whereas a larger or leakier space might require more frequent refills.
Does CO₂ supplementation replace the need for proper ventilation?
No. Ventilation is still crucial for controlling heat, humidity, and oxygen levels. In a sealed room approach, growers often rely on air conditioning and dehumidifiers while recirculating and supplementing CO₂. If you’re using a traditional open-vent system, you’ll need to replenish CO₂ more frequently due to exhaust.
Can I just use this calculator daily to maintain CO₂ levels?
Because your room will likely have continuous changes—like plant uptake, minor leaks, or ventilation—this calculator is best for initial estimates. A more precise method is a CO₂ controller or meter that detects ppm in real time and triggers a regulator or generator as needed.
How do I measure the actual CO₂ level in my room?
Use a CO₂ meter or controller designed for grow rooms. Some advanced models integrate with environmental control systems to adjust fans, humidity, temperature, and CO₂ delivery automatically.
DIY Approach: If you’re on a budget, handheld CO₂ meters can track levels manually. For automation, though, a dedicated grow controller is more reliable.
Will adding CO₂ help if my light levels are low?
CO₂ supplementation is most effective when adequate light is available for photosynthesis. If your lighting is insufficient, raising CO₂ might not improve growth much and could be an unnecessary expense. Always optimize lighting, temperature, and humidity before or alongside adding CO₂.
Why does the calculator ask for room volume and ppm difference?
To figure out how much CO₂ you need, we multiply the volume of the room (ft³) by the fraction of CO₂ (difference between desired ppm and ambient ppm, as a fraction of 1,000,000). Then we convert the resulting ft³ of CO₂ into pounds and grams.
Can I use this calculator to maintain CO₂ levels in a partially open grow space?
It’s not ideal, because any open room or active exhaust means you’ll lose CO₂ continuously. This calculator assumes a sealed environment for a one-time increase. If your setup has active exhaust or is partly open, you’ll need a more dynamic approach—like a controller with a CO₂ sensor—to consistently replenish your lost CO₂.