Every comment here has been excellent, I would like to add one
suggestion about feeding: The quality of the food makes alot of
difference in the amount of waste produced. Goldfish do not do as well
as many tropical fish on high protein diets, they need more vegetable
based diets. The basic difference in a carbohydrate and a protein (over
simplified) is the Nitrogen atom, which is converted in the fish's
waste to ammonia (NH3).
Carl
http://www.americanaquariumproducts.com/