[sussexchook]

I was told by a fellow poultry keeper that jeys fluid will kill the mites. Is this true? if so how much will I need to use?

[New shoot]

Jeyes fluid will kill most things Sussexchook, so I am sure it will work, but it will make the coop stink for ages. 

I've used Poultry Shield before and that works well.  It desiccates the mites, so you don't see the effects until a day or so later.  Then you see loads of tiny dust like bodies in the litter.  It is also odour free and safe for the chickens

[GrannieAnnie]

Jeyes fluid won't break down the jelly like stuff that covers the mites, poultry shield and/or diatom is best.  Jeyes is brilliant for disinfecting, but you really should leave the coop open for a few days to dry out properly, or it cold affect the chickens.