I don't think running water should be your problem. The contractor would have found a spring and groundwater doesn't run like a hose. I expect it is leaking due to construction. I doubt that it will seal itself at that rate.

It's not about the fish. It's about the pond. Take care of the pond and the fish will be fine. PB subscriber since before it was in color.

Without a sense of urgency, Nothing ever gets done.

Boy, if I say "sic em", you'd better look for something to bite. Sam Shelley Rancher and Farmer Muleshoe Texas 1892-1985 RIP Grandpa