We moved into this house 7 years ago in October, and the pond was here when we moved in. I knew nothing about water gardening, and tried to keep it in balance but not mess with it too much. I've now read several good books on water gardens and know a bit more.
The water is generally nice and clear. I have 8 or 9 big goldfish that have been in the pond for at least 4 years. They grow and thrive, and even produce babies occasionally!
Frogs lay eggs and have rock concerts in the pond, and I think that is a good indication that the water isn't accumulating bad stuff. Frogs are sensitive to pollutants because of their porous skin.
When it rains a lot in summer, there is an overflow, so there is some changing of the water. In spring and fall when we go a long time between rains, I add water but I do de-chlorinate it.
