I have six ducks all different breeds (Silver Appleyard, Rouen, Buff Orpington, Blue Swedish, Welsh Harlequin, White Layer) they all love to spend the day swimming and so far they eat EVERY pond plant I have put in/around their pond, even established Yelliw Iris. I have ended up "fencing off" (with Tenax plastic hardware cloth) sections for the plants in the pond and elevated the pond's bog filter so the ducks can't get to my bog plants. I have found that between the bog filter, the plants in the pond, and a "mechanical filter box" (I made from a heavy duty tote box and clean twice a month), my pond's water stays fairly clean and clear, and I am not wasting water by having to constantly drain their pond. I too am thinking of adding "reed type pond plants" to my pond. After reading the comments above I will give the cattail a try, albeit fencing it off until it can grow and become established. I forgot to mention my pond is 15x10x3ft. My older ducks always come to the side of the pond when I come to sit there...they are hoping "Mama" will throw them a Water Hyacinth treat. 😊 The first photo is just after I built the pond so the water is a bit "foggy" because of the pea gravel dust.