CO2 Tutorial - How to Add CO2 to a Grow Room

Plants need CO2 like we need oxygen. Fact.

CO2 + H2O + light = photosynthesis

Without carbon dioxide, plants can’t photosynthesise. In fact, if your CO2 level drops too low, plants won’t grow at all.

But how much CO2 is enough? When should you add CO2? How do you add CO2 to a grow room?

Here’s what you need to know. 

Yes. 

CO2 is needed for photosynthesis, which is how plants convert light into energy. 

If CO2 is restricted, so is photosynthesis (sugar production) and growth.

The thing is, there's only around 400 – 450ppm of CO2 in nature. At most, it can be as high as 800ppm in your home, just from breathing. This falls way short of the optimum 1200ppm.

Unless you add more CO2, plants won’t perform at their peak! Even a small amount of added CO2 can increase photosynthesis - and - your overall yield.

All the other effects CO2 has on plants, along with the extra sugars makes a big difference!

You’ll notice plants are stronger with thicker stems and branches. They'll be better able to cope with environmental extremes and pest attacks. With a thicker structure, plants will also be able to support a heavier yield.

Adding CO2 speeds up growth! It's great if you want to shorten your overall cycle, or just flip to flowering sooner.

When you add CO2, plants can photosynthesise more light. If you've invested in high end grow lights, adding CO2 will help you get the best out of your investment!

Once absorbed, CO2 helps plants perform in temperatures up to 30oC

You should add extra CO2 throughout your plant’s cycle. But they benefit from it most in flowering, especially at higher temperatures.

Target PPM: 600 – 700ppm

All the extra photosynthesis speeds up growth! Plants become bigger, greener and stronger in less time. This also means you can start flowering sooner when you add CO2 to your grow room.

Remember to flip to flowering when plants are just under half the size you want them to be at harvest.

Target PPM: 1000 – 1200ppm

During bloom, you’ll slash the time it takes to produce fruit and flowers.

It’s most important to add CO2 in the first 2 – 3 weeks of bloom, when flower production starts.

During flowering, the extra CO2 can help maximise high intensity lights. Remember – for photosynthesis plants need light + water + CO2. If they have the light and water and you give them the CO2, photosynthesis will occur at a higher rate.

Avoid dispensing at night. At this time plants aren’t using CO2 – they’re releasing oxygen.

Any more than 1200ppm is a waste of CO2 if nothing else! You’d have to go very high, but too much CO2 can also create a toxic environment.

For this reason, it’s key that you manage your CO2 dosing properly. If using propane or bottled CO2, make sure you use a CO2 controller. If you’re using CO2 bags, just make sure you don’t hang too many of them.

Even a small increase in CO2 can be beneficial.

There are three ways of doing it, depending on:

• how much CO2 you want to add
• what your budget is
• how big your grow room is

This is by far the easiest and lowest cost method.

You simply hang slow-release CO2 bags or bottles in your grow room. Carbon dioxide is slowly released over time.

The bags we sell are Exhale CO2 Bags & TNB The Enhancer Bottles, which are self-activated. This means they don't start releasing gas until they're in your grow room - there's no CO2 waste!

• Up to 3.65m x 3.65m (TNB The Enhancer)
• 1 bag per 4 - 6 plants (ExHale Bags)

• Slow-release CO2 bags or TNB bottles
• Rope Ratchets (for hanging)

• Smaller rooms where air is extracted.

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• Hang bags just above your canopy so they don’t create a shadow.

Pros
Low cost  Easy Natural release No running costs No excess heat or humidity No pilot light

Cons
Takes a week to activate  No control over CO2 output Bags can create a shadow if hung incorrectly

This is where you produce CO2 by burning liquid propane gas.

How does an LPG CO2 Generator Work?

As liquid propane gas is burned, CO2 is released. Some heat and moisture are also released as a by-product. In veg, the extra humidity is great. In flowering, you may need to remove it. 

Generally, you get more CO2 by burning propane than you get by using bottled CO2.

• Up to  30m2 (4kW AutoPilot Generator)
• Up to 90m2  (4kW Pro-Leaf LPG Generator)
• Up to 60m2 (8kW AutoPilot Generator)
• Up to 220m2 (10kW Pro-Leaf  LPG Generator) 

• Propane cannister (red / orange)
• LPG Generator (AutoPilot)
• UK Propane Regulator (Low Pressure)
• CO2 controller (with inbuilt sensor / analyser)
• Pipe cutters
• Leak detection fluid
• Hose clamp / gas hose clips

Note: If your controller doesn't have a sensor/analyser, you can buy both separately (e.g. Ecotechnics Evolution CO2 Controller + Ecotechnics Evolution CO2 Analyser) 

• Rooms with air-cooled lights or closed-loop rooms.