I use sand in my run and under my roosting bar. It is so easy to clean, I can't imagine ever changing. I ordered a ton of the construction grade stuff and still have a garbage can full so I was thinking of putting that in the brooder for easy clean up. Just wanted to make sure it's safe for the chicks
Read this and it is clear. Its good.
https://www.backyardchickens.com/t/751747/sand-in-the-brooder-its-worth-it