I have had my coop for about a year and figure it's time for a big cleanup. I clean the nesting boxes monthly but have not removed the ground material or washed down all the wood. Any ideas on what the best ground material I should use? Right now it's basically dirt but have heard that river sand is the best for the floor of the coop. I also need to clean all the wood and the "attic" area they sneak up too and poop up there! Any suggestions would be helpful!