Welcome to BYC. Glad you decided to join our flock. Sand is great for the coop/run floor and ground but you need to make sure that it is a very course sand (not fine like beach sand) and that it has been washed so that it is not dusty. Fine pea gravel (washed) will also work very well and there's no danger of dust with it. If you haven't done so already, definitely check out our Learning Center at https://www.backyardchickens.com/atype/1/Learning_Center. There is loads of useful information there. Please feel free to ask any questions you may have. We are here to help in any way we can. Good luck with your flock.