I give my chickens, chicks and ducklings 1 tablespoon Apple Cider Vinegar in 1 gallon water four or five times a month in a plastic container. Recently i was out of town and my mom was taking care of my flock . She gave them Acv in a stainless steel container. She didn't know that you are not supposed to use a metal container. Although i came home on time and the container was changed to a plastic one within 30 mins or so. I am still worried. Will it harm my flock in some way?