My girls have no interest in the dust bath I made for them. They ignored it completely when it was the size of a nesting box, I reduced the size to a smaller wooden tray. I have dirt, a little sand and DE in there (no access to ash). Every once in a while they will get curious about it but they definitely aren't demonstrating any bathing behavior. If they won't use it is there another way to safely expose them to DE to keep mites away?