Its 1 tbsp yeast to 1/3 cup sugar in a 2 liter bottle, filled 1/2 -2/3 of the way with luke warm water. The warm water activates the yeast, but if it is too hot it will kill the yeast - it is a live bacteria er something close to that. Mix the hell out of it for a minute or so, it last about a week, I shake mine every "morning" - sometimes I take it out at "night", prolly should take it out all the time
I have doubled the recipe and put it in a 1 gal milk jug or an old nute bottle. I havent found any extra results with this.
Sometimes I put the regular concoction in 1 gal jugs too its fine and more manageable.
To optimize the results, stick a hose in the top of the bottle and channel the co2 of to the top of your canopy so it will fall on the plants. Or put it behind a fan pointing up. I always have a fan pointed at the lights, this is where I set my bottles.
When I really used to keep up on it, I would have 3 of them going at a time. I had them in a 6x8x6 area at the time. I would put the first one in and wait 2 days, add the second wait 2 days, and add the third. About a day or two later I would be replacing the first and so on. I got up to 1800 ppm's in there though, so it must have done something. It would be better for smaller grows though - closet or box - pc or cabinet.