I have a hen that's had a runny nose for a few days....we have her isolated, and i was told to give tetacycline. I picked some up from the local co-op, and my wife and i mixed up a gallon. The problem is when we put it in the waterer, after a while it turns purple. Looks like purple koolaid. I just dumped it and added more, it turns purple again. The jug that i have premixed in the fridge doesn't do it, is it the sunlight causing it? Will it still work (if i can get the hen to drink it)? Any ideas?