Red Lake Earth(diatomaceous earth)How much and how to?

[yoursecret_1]

I think I might have red mites.And I was wondering how much RLE should I put in the coop and nesting boxes.One of my hens is sitting right now and in two weeks the chicks should be here.What should I do?
I clean the pen and coop every Sat.I just don't understand why I have mites.

 

[Mahonri]

Birds in the neighborhood can bring mites. One of the reasons I now try to always feed in the coop... the sparrows and doves stay out of there.