I think I got the info from something Doc Bud posted. I wait until the third week of flower to run my sulfur evaporator; during veg I don't get much branch or leaf clustering and those areas where air circulation can't get between the nugs (always the top colas for me) are where the dampness builds up and bud rot (then later grey mold) starts. I put the evaporator on a timer for 3 hours during the dark cycle; I imagine you could do it during veg, but I'm not sure if I would since I'm going to do it again in flower. I put 1 tablespoon of sulfur prills (small chips of sulfur) into the bowl and hang it about 16" from the top of the tent so the fumes will float downward onto the plants. You have to keep the tent clean and the humidity down after the sulfur burn or the grey mold spores will return; don't quote me on this because I'm probably wrong, but I think the sulfur vapors only suppress the spores and render them dormant, not kill them. It's damp around my area of the world right now.