DIY Co2 Yeast Recipe

The supplemental injection of Carbon Dioxide (CO2) is beneficial to the aquarium in many ways. When plants photosynthesize, one of the most important nutrients needed is Carbon, when carbon is lacking one will see considerable decline in plant growth and in some cases in the plants health. The addition of CO2 is essential in many planted tanks, to achieve full and lush growing healthy plants. Unfortunately, the high dollar price tags on the pressurized "professional" CO2 injection systems complete with tanks, regulators, solenoids, and diffusers/reactors along the complications that can come are more than enough to steer any prospective newcomers away. Luckily for those with a budget in mind, there is a recipe for generating CO2 along with several DIY methods of diffusing it into the aquarium water.

Here is what you will need:

• 1 plastic bottle of any size with the fitting cap, 2 liter soda bottles are popular and effective.

• 1 Electric drill, this can be replaced with a hammer but will not be as efficient.

• 1 Drill Bit (or nail if you are choosing to use the hammer), Be sure the bit/nail is slightly smaller in diameter than the airline tubing.

• Several feet of airline hosing, most if not all types will work fine.

• One tube of Aquarium safe silicone.

• Scissors.

• Pliers, may not be needed.

• 1 pack of Baker's yeast.

• 2 and 1/2 cups of sugar.

• 1 tsp. of baking soda.

• Luke warm water.

The science behind this recipe is rather simple. The yeast consumes the sugar as it multiplies, creating a CO2 by-product. This CO2 is released as a gas and can then be diffused into your aquarium. The baking soda is an aspect of the recipe that is not necessarily needed but will help to keep a steady output of CO2. Without it, the yeast will produce CO2, causing the hardness of the solution to drop, and a major ph swing making the solution very acidic. The acidic environment causes a die off of yeast, lowering the amount of co2 that can be produced. The baking soda raises the carbonate alkalinity of the solution, keeping the ph fluctuation and drop from being as dramatic.

Step 1: Get the drill and bit ready, along with the bottle cap. Make sure to drill on a surface that is allowed to get damaged in case you accidentally drill too far. Place the bottle cap on the work area so that the top is down, this will keep the top from cracking in case you apply too much pressure. Carefully drill a hole in the center of the cap. If you are using the hammer and nail, place the cap as instructed above. Place the nail in the center of the cap where the hole will be. In one strong and sturdy swing with the hammer, hammer the nail through the cap, making a nice hole for the hosing to fit through.
Note: the hammer and nail method are much less effective and run a greater risk of making an error than using a drill to create the hole.

Step 2: Take the scissors and airline tubing and cut the airline hose at a slant near the end so that it is pointed, this will make it easier to pull it through the small hole in the bottle cap. Push the pointed tip of the airline hosing through the hole, if needed grab it with the pliers and pull it through (it should be an extremely tight fit) . Don't worry about mangling the airline hose, you can always pull it through more and cut off the section of disfigured hose. Take the silicone and apply it around the airline hosing on the cap to create an airtight seal. Use it very sparingly on the inside as too much may affect how the bottle will screw on. Allow this to sit and cure for the time indicated on the silicone package (usually 24-48 hours).
Note: Do not cut the hose to length yet, there are few things worse than have a hose that is too short.

Step 3: Test the seal by screwing the cap onto the bottle and blowing as hard as possible into the hose. Listen for leaks, if any are present, remove the silicone and reseal it.

Step 4: Next up is to mix the recipe. Take your bottle, and pour 2 and 1/2 cups of sugar into it (you may save yourself some frustration and some time by using a funnel). Add 1/2 a tsp. of baker's yeast. Add 1 tsp of baking soda. Fill the bottle with luke warm water until it is 3/4 full. Shake the mixture very well.

Step 5: Screw the bottle cap onto the bottle making sure it is tightly fitted. Take the airline hose and attach it to your method of diffusion. This is a good time to cut the hose to length.

Step 6: Shake the mixture well every few days to ensure to keep the mixture going strong consistently and to keep any undissolved sugar from settling in the bottom of the bottle. After the mixture's CO2 production has slowed considerably, it is time to empty it and mix up a new batch of mixture. Simply follow the instructions again, making any adjustments that are needed to suite your situation.

This recipe is only what has working for my systems, I recommend altering this recipe to accommodate your needs or preferences while taking the following into consideration. The amount of yeast that you mix into the recipe will effect the speed and amount of CO2 that is put out, but this will mean that length of time it lasts for will decrease as it will intake the sugar much faster. On the other hand, mixing less yeast will result in slower CO2 production but it will last much longer. The amount of sugar mixed is a determining factor in the length of time that it will take for the mixture to run out. The more sugar, the longer it will last, the less sugar the shorter its life will be. Of course, there is a limit to the amount of sugar that can be dissolved into the mixture, so after a certain point, adding more is just a waste and won't make much difference. Therefore a balance between the amount of sugar, yeast, and what your needs are must be made to ensure that you get the most out of your mixture.

Diffusion is one the most important aspects of this DIY project. Irrelevant of the amount of CO2 your mixture is creating, without an effective method of diffusing the CO2 into the water the mixture will be wasting precious carbon and will not be very effective in aiding your system. There are several ways of diffusing the CO2 into your water, all ranging in effectiveness and complexity. My personal favorite method is to attach the hose to the intake of a filter or power head, this way the Co2 gets sucked in and mashed into hundreds of tiny bubbles that can then be dissolved, creating a very effective way of diffusing. I like this method because of its simplicity, its effectiveness and for the fact that it can easily be hidden from the casual observer. Other methods include complex and simple reactors that keep these bubbles in contact with the water for longer periods of time until they can be completely dissolved. Although these methods are more effective, they can be difficult to create and manage. Other ways are pumping it through air stones or commercial glass diffusers to create tiny bubbles. Both are effective, the latter being the most effective method. I plan to discuss these methods of diffusion in future articles.

In conclusion, this recipe will provide you with the ability to create and diffuse CO2 into your aquarium. As stated above, you may need to alter this recipe to fit your needs or preferences and to match your selected method of diffusion.

Echinodorus Amazonicus - Amazon Sword

Echinodorus amazonicus

Amazon Sword

A large E. amazonicus in the author's tank.

The Amazon Sword is one of my most favorite aquarium plants. Its large, lush green leaves make this giant, reaching over 20 inches tall, and the perfect candidate for being a centerpiece plant in larger aquariums. Although it’s a relatively easy, undemanding plant to have, its not suitable for all aquariums due to its tank busting size. My current specimen was a mere 6 inches tall when I obtained it, with 2 months it has grown to over 22 inches tall. The Amazon sword is a popular aquarium plant that has earned its place in the aquarium hobby as being a large, hardy, and beautiful plant.

The leaves of the Amazon sword are light green in color and when observed closely, three “veins” can be seen that run along the length of the leaf. The center vein being the thickest of the three, the other two are approximately ¼ the thickness of the main vein. Hair-thin veins interconnect these three veins by running perpendicular to them. The Amazon Sword easily grows to massive proportions, exceeding 20 inches in height if conditions permit. Often growing to the point of overshadowing other plants, eventually choking them out. The leaves range in thickness of about 1.5-2 inches in thickness at the middle of the leaf, and can reach a length of up to 24 inches, sometimes more under proper conditions.

A close-up of the leaf structure of the E. amazonicus. Notice the 3 main veins, and the numerous veins interconnecting them.

Sword plants typically are root feeders, meaning that they prefer to take in nutrients from the substrata rather than from the water column like other plants such as stem plants, and the Amazon sword is absolutely no exception. Its benefits, and prefers to have a rich substrate in which it can thrive. I have managed to grow mine in a sand substrate that is relatively low in nutrients, but I added fertilizer tabs to the base of the crown every couple of weeks and have seen wonderful growth from it. In my opinion, a deep substrata is also a beneficial factor in the growth and development of this plant, on my specimen, the root system is over 10 inches long. A deeper substratum will allow for proper root growth and will lead to a healthy plant, my substrata is about 2.5 – 3 inches deep. An Amazon sword that is doing poorly will discontinue growing new leaves, begin turning yellow around the edges of leaves especially younger leaves that are still in development, and the excess growth of nuisance algae on the leaves. The two main causes of these symptoms are often a lack of certain essential nutrients or a lack of proper or sufficient lighting. Amazons generally grow rather slowly but when given proper conditions, it will flourish and can quickly get to the point of choking out other plants. They prefer medium to high lighting, but will “survive” at lower levels. I keep my specimen at 2.3 WPG, with CO2 injection and it has thrived. The addition of CO2 is another factor that will increase the well being of the sword, but in my opinion, substrate nutrients and lighting are more essential to getting good growth with CO2 only helping the plant along.


Propagation of Echinodorus amazonicus is through two methods, runners and seeds. When submerged and in very a highly humid emerged environment, the Sword will send out runners, on which small plantlets will develop. Plantlets that develop on emerged plants will not develop roots until they are completely submerged. Once the plantlets have become of a good size, remove them from the runner while avoiding any damage to the runner because even after the plantlet is removed the runner will continue to develop more plantlets. The second method, by seeds, is a little more difficult to accomplish. Echinodorus amazonicus will develop small flowers when both submersed and when emerged. Only when the plant is emerged will the flowers open, at which time the fertilization process can be initiated by using a feather to spread the pollen. The seeds will begin to develop, often taking long periods of time.


In conclusion, the Amazon sword is a wonderful addition to any larger sized aquarium that harbors the appropriate conditions. Its size permits it to be both an accenting addition to an aquascape or the centerpiece. Providing the proper conditions for this beauty will give you the opportunity to enjoy one of the best aquatic plants in the aquarium hobby.