Six chickens, 160 sq ft run. Pretty much bare dirt in there before. I filled with about 6 inch deep of fallen leaves which they've now scratched down to a couple of inches. Would like to build up deep litter. Would you all fill it with another six inches? A foot? Is there any such thing as too deep? I'm sure they'd break them down if I filled it chicken-deep but it'd take them awhile. 
