DIY Co2 Recipe


DIY Co2 is an incredibly cost efficient way to start experimenting with CO2 for your aquarium. You can get started with CO2 for under $20 quite easily compared with $200 for a typical entry level commercial Co2 system. The most critical part of your DIY Co2 system is your recipe, it determines how long your Co2 will last as well as how much Co2 will be delivered to the tank per second.

The active ingredients that produce the Co2 are Yeast and Sugar, the yeast consumes the sugar and creates alcohol while releasing Co2 as a biproduct. Eventually, the alcohol produced will poison and kill the yeast ending the Co2 production at which point you need to empty your bottle and start again. By having more sugar/yeast the Co2 production is much more intense but won’t last very long, on the other hand less yeast/sugar will result in a lower Co2 production but the mix won’t need to be replaced as often.

The recipe I settled on gives me a consistent medium Co2 release for around 2 weeks after which production starts slowing until it stops completely after 3 weeks. This might work for you but feel free to adjust as needed to find a balance that works for you.

The Ingredients

  • 2 cups sugar
  • 1/2 tsp yeast (regular dry baker’s yeast is fine)
  • Water



  1. Mix some lukewarm water (not too hot) and a teaspoon of sugar in a small cup or bowl
  2. Add the yeast and mix with a fork vigorously until the water is bubbly. Let it sit for at least 10 minutes stiring every few minutes to keep the water oxygenated.
  3. Fill your primary container with lukewarm water to roughly 2/3rds full.
  4. Using a funnel, add the 2 cups of sugar to the primary container and then shake to mix and dissolve the sugar in the water.
  5. Add the yeast and water mixture you prepared to the primary container. Co2 should start producing within a few hours.

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