I have 8 pullets, 1/2 hatched middle of April and the other 1/2 hatched a week later. I've been feeding them chick grower with grit for chicks along side. When should I switch to a layer feed and add oyster shell to their diet? I also have a small round wading pool in the chicken yard full of dirt so they can have dirt baths. Just added that yesterday. The bottom of the coop (formerly a dog kennel) is lined with chain link to prevent dogs from digging out, or in, so dirt bath holes are probably not doable. Do you think that is adequate? Will they figure out what it is for? I have had chickens most of my life, but they were in the country and free range. "Backyard" chickens are a new thing for me. Thanks for the help!