It really only needs to be functional for a year in case the wet spots in the pond bottom turn out to be leaks into the water table. After that, a good permanent seal would be best on the drain. The valve is threaded onto the pipe, so it could always be removed by a diver.

Any advantage to adding FHM in early November if the pond gets enough water by then, or is better to add in spring?

Last edited by RAH; 10/07/17 04:49 AM.