I have two small ponds, approx 3x5, and 18-24 inches deep. I change the water daily, and wash the ponds out completely, since I do not have the option of constant running water. I feed cat food (very high protein), game fish food, grain, and layer. I supplement with feeder fish and mealworms. I also throw "grit" (crushed granite sold for gizzard fodder) in the ponds 3x a week. The birds pick it up off the bottom of the ponds like mad. Every breeder will have a different answer but I believe hitting the 30% mark on protein, consistent, clean, fresh water, and a good supply of grit are vital to day to day health.