This simple CO2 regulator is used to slowly release CO2 gases from the fermentation process of wine or beer using water and a few parts that can be found quite easily. It works by allowing CO2 to get out of the fermenter without permitting oxygen to enter. If oxygen was to get into the fermenter, it would stop the yeast from making ethanol alcohol.

Step 1: Gather the Parts.

Parts that you will need:
-One Cork
-3 inches of 3/8 inch hose
-Hot glue or other sealant
-A water bottle
-Clear film canister (usually available at any place that develops photos, ask for one)

Tools that will come in handy:
-Drill with 3/8 inch and 1/2 inch drill bits
-Hack saw
-Bench vice
-Belt sander/metal file/sandpaper

Step 2: Drilling and Fitting

First drill the 1/2 inch hole in the exact center of the bottom of the film canister. It should have a little dimple where the tip of your drill bit will sit nicely. Next, drill a 3/8 inch hole through the clamp. A bench vice helps. Once the holes are drilled, fit your tubing through the hole in the cork. You will need to calibrate and trim the tube, but we will get to that later. Next force the cork into the 1/2 inch hole in the bottom of the film canister a bit more than 1/4 an inch. After you these parts put together, you will need to seal the cork into the canister. I used hot glue but other sealants should work.

Step 3: Constucting the Cap Fixture

Now we need to construct the part that will act as the one way valve. You will need to sand down the cap to get rid of the lines or grip. To do this, leave the cap on the bottle and start sanding away. A belt sander would be very useful but if you do not have access to one of these you can sand it or file it down. You need to make sure that there is enough room between the cap and the sides of the canister. If it is an air-tight seal, it will not work properly. I just took the cap off and dropped it in and kept testing it. After you get it shaved down enough, screw the cap on tightly, remove that little ring of plastic, and cut the bottle right above the lip on the bottle. If you have no idea what I am talking about check out the picture. You will also need to sand off the rough edges.

Step 4: Putting It All Together and Calibrating

Lastly, you will need to punch a small hole in the cap in order to let out the gases. To calibrate your regulator you will need to adjust your tubing. Make sure the tube is nice and straight and protrudes about an inch into the canister. Fill it up with water to the top of the hosing and drop in the cap part you just made. Push down until the gas is released and some water comes out of the bottom, lowering the cap to a bit more than halfway. Pop on the cap and SLOWLY blow into it. If you blow to hard the cap will just stick to the top. You just have to slightly exhale to get it to work. I've also attached a video of it working on a jug of fermenting grape juice. Enjoy and I hope this was helpful!