Hello! Congrats on your new ducklings and I support you saving the smallest one and the mate! Plus I am a huge fan of runners! I see you got lots of great answers to all your questions. I’ll just add in, I use apple cider vinegar once every 3 months and mix it into her drinking water to worm her. I do it as a just in case! 4 tablespoons to a gallon of water, but don’t use metal because ACV is a light form of acid so it can release (I think) ?zinc? into the water if dosed too high or release metal toxins if in metal. It works great for all pets and people too!!!