Well reviews sound good on the enzyme spray though I can't confirm or deny that it works, as I've never tried it. A lot of the reviewers seem to be spraying it around randomly without an actual infestation, and very few confirm what "bugs" they actually have - so I don't know. If it works then...
You need to check the coop at night in order to look for a roost mite infestation - wipe a paper towel along the underside of the roost and shine a flashlight in any seams in the wood.
I have no idea what's in the enzyme spray (need a direct link to product) so I don't know if it's effective...