OK I am totally unfamiliar with this stuff but we just bought some baby chicks and the guy at tractor supply said to buy some and add it to the water-- trouble is, we don't know how much to add...the bag says 200 mg for 5 gallons, but we can't weigh it!! is that about a teaspoon full? Any idea? He also said to give some to our year old hens--that is would be good for them. Any comment? Thanks!