I dust out my coops with diatomaceous earth. I have treated leg mites by dipping the chickens legs in vegetable oil and letting them run around the yard. They get a mud cast which cracks and falls off after a few hours leaving legs very clean.
My chooks free range, I give them course grain, cooked brown rice, vegetables and salads, A chick hatched last night from a very thick shell. I couldn't view over an led candler on the incubator. I think its fat healthy hens with a lot of calcium and Vit D.