I was just going to suggest a sand bath spot. My grandma had chickens for many years and never had a mite problem. Her chickens had access to a sand bathing spot. Of course a person could always add DE to the sand, if they wanted.Don't waste your money on DE. It will do nothing that sand can't do.
That's what I would do too, along with the Ivomec:My coop was then sprayed to dripping with permethrin premise spray after removing bedding.