the only drawback to foliating (spraying leaves) is fungus and mold buildup on the wet leaves. i use 5 cups sugar with 6 packets of active dry yeast and water in a soda bottle.i use two of these setups. they last for about 3-4 weeks for 20 plants in a closet and it costs about $5 every time! this creates enough co2 for my babies. at night I use a curtain across the doorway (they sit in an unused closet in basement) to further increase the buildup of co2. This is just one more cheap way to get them co2