I've seen a lot of recipes using 2 cups of sugar in a 2 liter bottle. Mine wouldn't work that way and after searching, I found you can put TOO much sugar in it.
So in a 2 liter bottle, I used 1 teaspoon of yeast, 1 cup sugar, a little baking soda and water. I proofed the yeast in some lukewarm water with a little bit of sugar in it before putting it into the bottle. In the bottle I put roughly a cup of very hot water and the sugar so that it dissolves really well. Then added cold water to the level I wanted which made it about the right temp. The diffuser is a power head method. Don't forget that the diffuser is important too.
My plants are pearling and the production has been pretty consistent for nearly a week now. If I wanted more, I think I'd do two bottles with that recipe rather than adding more sugar or yeast to one bottle.
Don't forget a gas separator bottle!
I filled the 2 liters up to the label as many recipes instructed and get some solution coming up into the tubing. The gas separator will catch that and prevent you from pumping that solution into the tank.
All it is is a bottle (mines a 20 oz bottle) with the tube from the reactor going in then a separate tube going from the gas separator bottle to the diffuser. It took longer to find the right size drill bit than to make it. :D