DIY CO2 PRIMER

Why DIY? Pressurized CO2 systems are an expensive investment. You may not be sure it will be worthwhile, and would like to try CO2 injection to see how it...See more » Why DIY? Pressurized CO2 systems are an expensive investment. You may not be sure it will be worthwhile, and would like to try CO2 injection to see how it affects plant growth before spending the money for a pressurized system. Or maybe you have 3 tanks in 3 different rooms, which would require 3 pressurized systems. Perhaps you are on a student budget and just can't afford a commercial system. Or maybe you have a 10 gallon tank and figure a full CO2 system would be overkill. For any of these reasons, a DIY CO2 setup would be worthwhile. It costs very little, can be set up in a single day, and only requires a few minutes of maintenance every few weeks. And the difference to your aquatic plants can be dramatic. So How Does It Work? A yeast culture is started in warm sugar-water inside a closed bottle with tubing leading into the aquarium. As the yeast begins to reproduce and metabolize, it uses the sugar for energy and begins to produce CO2 as a byproduct. The CO2 builds up a slight pressure inside the bottle and then exits through the tubing into the aquarium. Various diffusers and reactors can be used to disperse the CO2 throughout the tank. The yeast culture continues to produce CO2 until all the sugar is used or until the alcohol level in the bottle reaches toxic levels. How Do I Set Up a System? You will need a 2L soda bottle or similar-sized glass or plastic container with a screw cap which fits tightly, some standard airline tubing, and silicone glue or Plumber's Goop from the hardware store. Drill or punch a hole into the bottle cap to the approximate size of the airline tubing. You can use a 1/4" electric drill or a heated nail or any other way you can devise to put a hole in the cap. Insert the tubing so that it extends 1/4" to 1/2" into the bottle cap. Glue the tubing to the cap on both inside and outside. Allow to dry overnight. At some point on the tubing, insert a check valve so that gas can exit the bottle but not return. This will prevent any siphoning from the tank into the bottle. RECIPE: Using a funnel or rolled up paper, pour 2 cups of sugar into the bottle. Add 1/4 teaspoon of baker's yeast and a pinch of baking soda. Pour in a little warm water (NOT hot) and mix around to dissolve the sugar and yeast. Then fill to the shoulder (just above the label on a soda bottle) with warm water. Shake well and cap with the tubing-cap assembly. Run the other end of the tubing into the aquarium. This setup will serve an aquarium in the 10-30 gallon range. To disperse the bubbles, you can do any of the following: - place the tubing into or under the intake to the canister, powerhead or power filter, allowing the filter impeller to disperse the bubbles. Caution - do not place the tubing in any high flow area which might create a vacuum in the tubing and collapse the culture bottle or siphon the culture into the tank! - place an airstone on the end of the tubing and anchor in the aquarium. - make a simple reactor. Plans can be found at http://www.thekrib.com/Plants/CO2/ Airstones and diffusion bells are less efficient than reactors and filter dispersal. I've Seen Other Recipes Out There - Why Should I Use This One? You can use any recipe that works for you. The above recipe is a good one because it provides enough sugar to fuel the yeast for several weeks. In addition, it begins with a low population of yeast so that the culture will increase over a longer period of time and thus extend and modulate CO2 production. Adding more yeast will give a greater burst of initial CO2 output, but then the yeast will use up the sugar more quickly and die off more quickly. Using less sugar will decrease the overall lifespan of the culture. The baking soda helps to maintain pH and provide greater tolerance to the buildup of alcohol in the culture medium. My Yeast Culture Isn't Producing Any CO2. Why? Your yeast starter may be old. You can test its viability by adding a pinch of yeast to a little warm water. Wait 15 minutes or so. You should see some foaming on the water surface. If you don't, the yeast culture is too old and youSee less »