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The Best DIY CO2 Recipe and Setup


Posted May 6, 2012 by

DIY CO2:  A Great Alternative to Pressurized CO2 Rigs

Thinking about adding CO2 to your planted aquarium but can’t justify spending $200+ on a pressurized rig? Don’t worry, there is an extremely cheap solution that is safe to use, and produces great CO2 output…  yeast! Starting a DIY CO2 yeast and sugar set up is fast and easy. This article contains my super-secret (Ok, ok…  It’s not really a secret at all) DIY CO2 recipe that will supply your 1-20 gallon aquarium with constant CO2 supplementation for at least a couple weeks. The best part about this solution to the CO2 dilemma is that it costs under $10 bucks to get started and to have CO2 bubbles streaming into your tank within 24 hours.

How Does DIY CO2 Work?

This DIY CO2 recipe uses yeast to create CO2 as a product of the yeast’s interaction with sugar.  This reaction is similar to the process of baking bread. When yeast cells absorb sugar, they give off alcohol and CO2 as products of this reaction. When baking bread, yeast from the air gets incorporated into the batter and trapped within it. As the yeast gives off CO2, the CO2 causes the bread to rise, forming the air bubbles observable in pieces of bread. By adding sugar and yeast to an airtight bottle, the CO2 that gets produced can be harnessed and released into the planted aquarium.

The basic mechanism works like this:

Yeast + Sugars –> Alcohol + CO2

DIY CO2 Recipe

Here’s what you’ll need to get started:


  • 2 liter Plastic Soda Bottle
  • Airline Tubing
  • Silicone
  • Drill


  • 1.5 – 2.0 cups Brown Sugar
  • 0.5 – 1.0 tsp Active Dry Baking Yeast
  • Warm water


a diy co2 apparatus

A DIY CO2 setup.
Credit: kirsten.elise

Now that you have all of the supplies you’ll be needing, we can get started with assembling the CO2 apparatus. Basically, the goal is to have an airtight vessel with an outlet hose at the top for the CO2 to escape into (and into your tank). Note:  Be sure to use a plastic soda bottle for your DIY CO2 recipe. These bottles are designed to hold pressure from CO2.

Take the cap from the 2 liter soda bottle and drill a small hole into the center of it. The hole should be slightly smaller in diameter than the airline tubing used. Insert the airline tubing into the cap, and create an airtight seal around it with silicone. Let this dry for a day or two to ensure that the silicone has cured.

A check-valve should be inserted at some point between the CO2 apparatus and the aquarium. This will stop aquarium water from making its way back to the CO2 apparatus.

A second, smaller bottle should be used in between the aquarium and the CO2 apparatus. Connect this by drilling two holes into the cap of the smaller bottle. Run the tubing from the CO2 apparatus to the 20oz bottle. The tubing should go to the bottom of the 20oz bottle. Another tube should be secured from the second hole in the cap. This second tube will run to the aquarium.

A diffuser of some sort should be placed at the end of this tube and into the aquarium. Wooden diffusers or airstones work fairly well. Another option is placing the tube right into your filter intake. The purpose of the diffuser is to break up the CO2 bubbles into a fine mist of microbubbles that can readily reach the plants in your tank. Any CO2 bubbles that reach the surface and break are wasted, so a quality diffuser is highly recommended.

Add the brown sugar and warm water to the 2 liter soda bottle. Enough water should be added so that the 2 liter bottle is filled about 3/4 full. Thoroughly shake this mixture to make sure the sugar is completely dissolved into the warm water. The yeast can be added after the sugar is dissolved. Immediately cap the 2 liter bottle and be sure that all of the tubes are securely connected to the caps. If your bottles and tubes are airtight, you’ll begin to see bubbles diffusing into the aquarium through the diffuser.

The mixture should produce steady CO2 bubbles for about 3 weeks, give or take a few days. Congratulations, you now have CO2 supplementation to your aquarium for under $10! This DIY CO2 recipe is definitely the best one I’ve ever used in terms of stable CO2 production, and runtime for the mixture.

Final Notes

CO2 is not required in low light tanks (1wpg) with basic plants such as Anubias and Java Fern. If your lighting is over 2wpg, CO2 supplementation is almost a necessity to fight algae and to promote plant growth.

If your tank is bigger than 15-20 gallons, you will need to make 2 separate mixtures of this DIY CO2 recipe and run them at the same time in order to supply a decent amount of CO2 to your plants. This DIY CO2 recipe won’t work for tanks larger than 55 gallons; a pressurized CO2 rig would be required.

If you have another DIY CO2 recipe you’d like to share, please do so below!

Featured Image Credit: etcavanaugh


Corey is the primary author and editor on Critterhub. With over 20 years of pet care experience, his interests lie mostly in aquaria and herpetology. Corey has a degree in Biology, and has completed many research projects involving herpetology and other animals.


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