Don't have a link, but I use three tablespons of yeast and three cups of sugar in a gallon jug filled about 3/4 full with water. I use one jug each for about 8 sq ft. Shake each day to see if it still bubbles, recharge when no more bubbling. If you use a cap on the bottle it has to have some holes to let the gas escape. Some people use a balloon with pin holes punched in it on the top of the jug to dissipate the gas produced.