I was recently working on a project where I needed some CO2. Unfortunately, my CO2 fire extinguisher was empty and I didn't have the time to go get it refilled. I decided to quickly make a CO2 generator with some stuff I already had lying around the house.
Step 1: Mixing the CO2 Generating Ingredients
I begin by preparing a mix of 2 parts Sodium Bicarbonate (aka baking soda) and 1 part Citric Acid (aka Lemon Salt). Both of these ingredients are readily found in the baking isle at your local supermarket in case you don't have them in your house to begin with.
Step 2: Store the Ingredients in a Dry Place
Once the mix was prepared, I put it away in some plastic containers for later use. You can see how fizzy the mixture is when mixed with water and activated.
Step 3: CO2 Generator Made With 40mm (1 1/2") PVC Pipe
I then began building one of the two CO2 generators I made. The first one consists of PVC piping of approximately 40mm in diameter together with an end plug and a screw-on top plug.
Step 4: Drilling the End Cap and Inserting Plastic Tubing
I drilled a 6mm hole in the end plug so that I can insert some plastic tubing. With the hole drilled, I inserted the tubing and set it with some 10 minute epoxy.
Step 5: Securing the Tubing With Epoxy
With the tube quickly set, I proceeded to fill the area surrounding the tubing with a more liquid plastic epoxy which sets over night.
Step 6: CO2 Generator With a Fizzy Drinks Bottle (pop, Soda Bottle)
With the first generator complete, It was time to turn my attention to the second generator. This one was made using an old fizzy drinks bottle that I salvaged. If you want to make this type of generator, make sure to use a bottle which held a fizzy drink and not just a regular bottle of water or juice. It needs to be able to maintain some pressure.
With a 4mm hole drilled into the cap, I inserted some aquarium silicon tubing which has a valve attached to one end. I also filled the surrounding area with a liquid epoxy mixture and set it overnight.
Step 7: Assembly and Testing
By the way, if you premix your Sodium Bicarbonate with the Citric Acid, make sure to store them in a dry environment not like I stored them. Otherwise you may get some premature fizzing. However, on the plus side, you have ready made Bath Fizzies.
Luckily the mix still worked and I managed to test it. Finally, I also tried the fizzy drink bottle version of the CO2 generator and it also worked well. This bottle generator works great if you have an aquarium that has many plants in it and want to add some CO2 to your tank.