Once they're at least 2-3 months old it's fine to go without food and water at night - I always gradually get them used to it - removing food first. They always need water if they have food available. I second what Miss Lydia said about hardware cloth and researching how to make it predator proof for the dangers in your area. We enclosed our run with hardware cloth going under concrete blocks that are buried. They also an area fully enclosed by wood that they sleep in - it has windows for ventilation and I can partially block them with plastic in the winter to keep warmth in. Ducks sure do need somewhere to swim and keep clean. It's part of the challenge of keeping ducks - it's a lot of work as their ponds need continual cleaning, but they're waterfowl and that's what they're made for and they love! Good luck with your babies!