I saw a pond this weekend that had to be the most beautiful
manmade pond I've ever seen. The pond had two wells.
One well fed clear water in and the other allowed it
to drain out. Constant fresh water. No filters just clear
circulating 73 degree water.

The pond was about 40' long with varying depths, as
deep as maybe 4.5'. Koi, Oscars, Cichlids and various
other tropical all living together.

Owner said that he occassional swims in it to clear out debri
or just to cool off.