Hi there! First time chicken keepers here and we are wondering what is best to use on top of the dirt floor in our 11 x 12 chicken run. Our area is prone to flies and we need to keep smells at bay as there are neighbors not too far away. So what are everyone's suggestions? Hay, straw, wood chips, pine shavings, leaves? And how often do you replenish, add to, or clean it out completely?