How to Make Homemade CO2 for a Planted Aquarium

Next to strong light, a dose of CO2, or carbon dioxide, helps aquarium plants thrive. Like their terrestrial counterparts, underwater plants take in carbon dioxide and give off oxygen as they grow. When oxygen production is high, hobbyists can see thin streams of oxygen bubbles coming from the plant leaves. Carbon dioxide systems that use pressurized tanks can be complicated and expensive to set up, but a home hobbyist can add carbon dioxide to the tank with some common household items.

Things You'll Need

  • 2-liter empty plastic bottle, with cap
  • Drill
  • Silicone tubing
  • Aquarium-safe silicone glue
  • 2 cups sugar
  • 1 tsp. baking soda
  • 1/2 tsp. active dry yeast
  • Air stone
  • Canister filter
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Instructions

    • 1

      Drill a hole in the bottle cap that is just slightly larger than the diameter of the silicone tubing. If necessary, a nail or a screw can be used for this step.

    • 2

      Insert one end of tubing from the outside of the cap to the inside, so that it extends about 1 inch. The longer end of the tubing should be coming out of the bottle.

    • 3

      Secure the tubing to the cap with aquarium-safe silicone glue. Use the glue on the inside and outside of the cap.

    • 4

      Add the sugar, baking soda and yeast to the bottle. Add enough warm water to fill the bottle to 4 or 5 inches from the top.

    • 5

      Seal the bottle with the cap, and shake well to mix.

    • 6

      Attach the longer end of the tubing to the intake of the canister filter. Or, if you do not have a canister filter, attach an air stone to the longer end of the tubing and place the tubing and air stone in the tank. The goal is to dissolve the carbon dioxide gas in water.