Ok, first off, use NON salted seltzer or soda water. Spray as much as you like as long as you have a fan on simulating a good breeze in there. The reason your going to spray UNDER the leaves is because
A- leaves take IN co2 from the bottom and push o2 out the top of the leaf.
B- bugs hang out under leaves and they hate water!!
You do not mist the leaves with the light off, this is when leaves are also emitting co2 as well as oxygen. Misting with no air movement or inadequate air movement can cause mold.