How to Add CO2 to a Planted Aquarium

If you want to make your aquarium as authentic to a natural environment as possible, real plants can̵7;t be beat. With plants that require low light levels, additional carbon dioxide (CO2) is not needed. However, the more light you use in your aquarium, the higher the plants̵7; CO2 demand and supplemental CO2 is necessary. The increased plant growth resulting from additional CO2 also reduces the amount of algae found on aquarium rocks and plant leaves, making for a cleaner looking tank. Automatic systems using pressurized CO2 are perfect for large tanks, but rather expensive. Here, we will focus on a homemade system that will do the job for any aquarium.

Things You'll Need

  • Plastic container with tight fitting lid, 48-64 oz.
  • Hand drill (alternate: a hammer and nail with narrower width as the tubing)
  • Scissors or razor blade
  • Silicon or CO2 resistant tubing, narrow gauge
  • Pliers or tweezers
  • Sugar
  • Water
  • Yeast
  • Bubble diffuser
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Instructions

    • 1

      Obtain a plastic container with a tight fitting lid, 48 to 64 oz. and silicon or CO2 resistant tubing, narrow gauge.

    • 2

      Remove the lid to the plastic container and select a drill bit (or nail) roughly 1/2 to 2/3 the width of the tubing. Using the hand drill (or hammer), drill a hole into the center of the outer side of the container̵7;s lid.

    • 3

      Use the scissors or razor blade to cut off one end of the tubing diagonally and thrust the resultant point through the hole in the lid from the outside. Use pliers or tweezers to pull the tubing through half an inch or less. Note: If the seal between the lid and tubing is not airtight, the system will not work. The tubing should not pass easily through the hole in the lid.

    • 4

      Combine in the plastic container 3/4 cup sugar with 4 to 5 cups clean water (preferably distilled; it must be nearly sterile) and 1 tsp. or less yeast. The ratio need not be exact. Seal the lid with the tubing tightly onto the container.

    • 5

      Set the container beside your aquarium and trim the tube with the scissors or razor blade so that it will extend only to the bottom of the inside of the tank. Affix the bubble diffuser to the free end of the tube and lower it into the tank. The diffuser will break the larger bubbles into many tiny ones, though several alternative methods exist to break up the bubbles, such as air stones.