My girls are in a run/coop, not free range. My run is 16' x 8' and has a metal roof and I currently have 7 chickens. My coop is 6' x 4'. I clean it every week or if it rains. I just heard about a dusting bath. Since my run is covered, can I build an area in the run? What needs to be in it? What size does it need to be? I really want them to be happy and healthy. Any advice will be greatly appreciated.