Just dirt for us! I throw a big pile of leaves in there whenever I rake, too. That gives them something to do, and mulches the leaves down for me to remove and compost later.Cool! I've been debating only using it in the actual coop for litter - especially to help keep feet/eggs clean. do you use any bedding in the run? My run is just loose dirt since I dug out the pad and laid wire down, then put dirt back over the wire.