it doesnt take alot of PAM to kill. You need to treat every enclosure, and I would suggest spraying a rag for 2 seconds and whiping that rag on your rack rims and rims of your tubs/tanks or w/e your using. PAM will stay active on any surface even if you wash the surface for atleast 30 days.
the Mites have to make contact with the surface to die. so it may take a few weeks , and possibly months before you completely erradicate your infestation. Understanding how mites live is the key to knowing how to use PAM correctly. if you have any questions, call Bob (owner) of pro-products and he will help you. hes an awesome guy!