The Adams flea and tick works better and they don't build up a tolerance against it. But in my opinion if you keep a clean yard as far as parasites and don't introduce new birds that you know nothing about then there isn't as much of a problem to begin with. Also wood ashes in a box of the coop the chickens will dust in it naturally and want have any issuesI have heard that too about the Adams brand. I think some people just use the concentrate as they have large flocks and it is more cost effective. The Adams can be picked up at a lot of pet stores.