I heard a lot of stories about how messy ducks are. I want to get 3 to 6 in April. The coop I am planning them to live in is (estimate)about 80 square feet. I am planning to use sand bedding, with a large dog house with straw in it for winter for them to keep cozy in. How do you keep your duck enclosure clean? How messy will 3 or 4 be?