Get a 1.89L bottle (ocean spray or v8 work). Drill a hole in a put an airline tube in the top (preferable a co2 airline tube).
Next if you want to do a diy bubble counter, you can use a antipasta jar or glass jar of a sort and drill two holes in the top. fill halfway with clean water and have one tube go down into the water, and on near the top of the bottle (NOT IN THE WATER). The tube that is in the water must be the hose connected to the 1.89L bottle. The other airline hose with leave your bubble counter and be connected to check valve. Then have a hose connected from the check valve to the tank and use whatever method you want to allow the co2 to enter your tank. Mine is connected to a power head at the moment until i can get the smaller one I want. The formula will be 2cups sugar, 1/4 tea spoon yeast, and 1/2 tea spoon baking soda. Will the bottle 3/4 of the way with warm water. Next add in the 2cups sugar and mix until the water is clear. let it sit till room temperature. when at room temperature add the yeast and baking sode and slosh the water back an forth just to get the yeast and baking sode from sitting on the top. close the bottle and let it go on its own. Ill try and post a picture of mine tomorrow. Im in the middle of a DIY 55gal stand......my fish room has been changing over and over and over for the past 3months...
Don