We are in the process of building our coop. We live in Maryland, very hot and humid right now. We just have a backyard, not acreage. The run is done and covered and the chicks are in there, sleeping in a box/cave at night. We have twelve 6 week old chicks. The coop will be 4' x 12' and the run is 12' x 12'. I tried to do some research on the deep litter method for the run and wow! there is a lot of info. Too much! So, I have a few questions about it. I don't have a lot of natural stuff to collect from the yard to put in the run. I will start collecting, but in the meantime, what can I buy for the run? Right now, there is some yard clippings, some straw, and some pine shavings. Can I use some straw? Can I use the pine nuggets that are sold at Lowe's? What about hardwood mulch? Pine shavings? If I understand correctly, the run material should be different sizes so that it doesn't compact down. Can I use some of all the above? Also, as of yesterday, we started having some flies in the run. Is that because I need more stuff in there? Thanks!