I'm glad my experience could help you out. As you've discovered good information on ducks seems to be too hard to find. I agree that as long as they are doing well and seem content then what more can or should we do? Mine love the pond and nothing else. The only time they get out of the water is to preen or eat. It was 18* this morning and so much frost I thought it had snowed and there they were swimming happily along. As soon as they saw me they started quacking and heading toward me wanting breakfast. While I attended the chickens they finished and were back swimming before I got back to the house. Life is good! lol
Best of luck with your quackers.