DIY: CO2 Generator for an Aquarium

CO2 allows all sorts of plants to be added to your aquaria.

The addition of CO2 to an aquarium affords the fish enthusiast with the option to add an array of aquatic plants to the tank, but pressurized CO2 can often be very costly, especially for someone new to the planted tank hobby. Another much more affordable choice is DIY CO2 made with a few simple ingredients from the grocery store.

Things You'll Need

• Drill with small bit
• 2-liter bottle (clean)
• Scissors
• Aquarium silicone
• Silicone airline tube
• 2 cups sugar
• 1/2 tsp. active dry yeast

Instructions

1. Drill a small hole into the bottle's cap, making sure the opening is just large enough to fit the airline tubing snugly through.

2. Cut the airline tubing to the length you will need; make sure there is enough tubing to go from wherever the CO2 bottle will be housed, to the inside of the tank, with a little extra tubing for "wiggle room."

3. Insert one end of the airline tubing into the bottle cap from the top, allowing approximately 1/4 to 1/2 inch to protrude into the inside of the cap.

4. Apply a bead of aquarium silicone around the tubing on both sides of the cap, and set aside to dry for at least 24 hours.

5. Fill the 2-liter bottle with 2 cups of sugar, and add the yeast. Fill the rest of the bottle to within 3 inches of the top with lukewarm (not hot) water. Cover the bottle opening with your hand or a spare cap, and shake vigorously to mix.

6. Screw the cap with the tubing firmly onto the bottle, and connect the free end of the tube to the intake of your power filter or powerhead. Alternately, you can purchase CO2 diffusers or an air stone to act as bubble diffusers within the tank.

7. Replace the CO2 sugar/yeast solution every three weeks.

Tips & Warnings

• When applying the silicone, it can be tricky to keep silicone from getting all over the inside of the bottle cap. To help avoid this, pull 3 to 4 inches of tubing through the bottle cap, and apply a bead of silicone around the tubing (an inch from the end). Now gently pull the tubing back out of the cap until the silicone bead makes contact with the inside of the cap, sealing the inside.

• Never leave an active CO2 bottle completely sealed; this could cause potentially dangerous and very messy bottle explosions to occur.

References

• GPodio: DIY CO2

Resources

• The Planted Tank: DIY Yeast CO2