How To Make a DIY CO2 Generator For The Grow Room

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How To Make a DIY CO2 Generator For The Grow Room

All plants, including cannabis, need carbon dioxide to survive. It is used during photosynthesis – the process by which plants produce energy for themselves by converting water and carbon dioxide into sugar and oxygen.

As long as you keep a constant supply of fresh air coming into your grow space, your cannabis will be fine. However, going the extra mile to boost carbon dioxide levels above the norm can really improve plant growth and the resulting yields.

Saying this, unless you are a big time grower and can afford a professional solution, getting the equipment to do this can be out of reach. The good news is, you don’t need the professional stuff to get results. It is possible to make your own DIY carbon dioxide generator for very little cost at all. These methods do not offer the same degree of quality and control as the professional methods, but for a small grower, they go a long way improve results.

Option 1: Yeast Fermentation

A great way to generate extra carbon dioxide is to have a bucket or vat of yeast working away in your grow room. Yeast is a living organism, and is used in the brewing of alcohol. If you supply a colony of yeast with water, nutrients and sugar, it will happily consume them, producing an ample amount of carbon dioxide and alcohol as a by-product.

Please Note: Brewing alcohol is a whole other area of law you need to take into account. Laws will vary from country to country, so please make sure you are aware of the laws regarding producing your own alcohol where you are. It may not be your intention to produce it, but it will be made none the less.

To do this you will need:

A 5 liter demijohn (you can pick this up easily online, or anywhere that sells brewing supplies)
1tsp of dried active yeast or a few grams of bakers yeast
Warm water
1 cup of sugar
2 pureed tomatoes as a source of nutrients


1. Fill your demijohn with warm water (but not right to the very top). The water needs to be at least 21 degrees Celsius, but no hotter than 40. This is the temperature range yeast likes to work at, and you will find it is most optimal closest to normal room temperature. If you let it get too hot, the yeast will die.

2. Add your sugar and tomato paste into the demijohn and mix it until it dissolves.

3. Now add in your yeast.

4. Ensure that the temperature of the mixture is maintained. This should not be too much of a concern in a warm grow room.

5. After a few hours, your mixture should start gently bubbling. This is the yeast doing its job producing carbon dioxide.

6. Place the demijohn close you your plants.

There you have it, now you know how to make your own basic yeast based carbon dioxide generator. You can keep the yeast colony going by pouring out some of the solution every week or so, and replacing it with fresh water and a few teaspoons of sugar. This will ensure that the yeast has a continual supply of food, and doesn’t poison itself as the alcohol concentration increases. If left without a fresh supply of water and sugar, the yeast will die within a week or two.

You can also use a demijohn bung and piping to make the release of carbon dioxide more targeted. This bung (which has a hole in it for the piping), fits neatly into the top of your demijohn. You can then use piping to direct the carbon dioxide directly onto your plants. Bungs and piping can be bought anywhere that sells brewing equipment.

Option 2: Vinegar And Baking Soda

Another way to produce carbon dioxide, without having to produce alcohol, is by combining vinegar and baking soda. However, as the reaction between baking soda and vinegar is very rapid, it doesn’t last very long.

To overcome this, you will need to set up a system that slowly drips vinegar into a tray of baking soda. This way, all your ingredients don’t get used up at once, producing a steady stream of carbon dioxide.

We would personally recommend using yeast, as it is much less technical to set up. And much less erratic in the amount of carbon dioxide produced.

As a closing note, it is worth knowing that carbon dioxide enriched cannabis will become more demanding than regularly grown cannabis - it will need more space, require more nutrients, and use more water. So make sure to take this into account when planning out feeding schedules and grow spaces. The amount it requires will depend on the strain and level of carbon dioxide – it may come down to a little bit of trial and error. Good luck!