I might sound like a broken record to those that know me, but I can't say it enough: Using wood ashes for your chickens saves you money. We store them (fireplace ash only, not BBQ coals, etc) and when needed, mix 2 1/2 parts ash to 1 part sand for the chickens to do their dust bathing. And guess what? It keeps mites away. It's been over a year since the last time I bought the bottled mite spray. That and painting the coop with hydrated lime has worked great so far!