And, because I'm cheap, I use construction sand. Buy it in 50# bags at any home improvement store, less than 7 bucks. Don't use play sand, that's been screened to just small sand. Construction, or all-purpose sand, has bits of granite, little pebbles, and sand. I save some aside as grit, and put the rest in cat litter pans in covered areas for the chickens to scratch in, dust bathe, etc. And some I just tossed in their favorite sun-bathing spots.