soda water, sparkling water, i think they all contain carbon dioxide to give them a punch. the key is carbon, that is what the plants need. i noticed in "I Grow Chronic" that this method was used and it appears to work. i have done it to my plants once already with no adverse effects. i will continue to do it. as to whether to do it on the buds or just the leaves, i would think only the leaves need it, that is where the carbon is used. spraying on the buds can't be helped at times in an attempt to get the leaves, but i don't see it hurt mine any.