I need to drain my 70 year old, 2 acre catfish pond so i can excavate the several feet of muck at the bottom. It has an overflow drain which I believe is 6 inches. I don't want to break the dam so I am trying to decide if I can siphon through the existing overflow drain or spend $1000 and build a natural siphon system out of 6 inch PVC over the dam. Anyone have any experience siphoning through the overflow drain? Most of the catfish have died out and the goal is to fill the pond back up and introduce some kind of bass into the pond.