Pond Boss Forums POND CONSTRUCTION Renovating a Pond or Lake? Penstock/pipe flow has mysteriously reduced?

If the head is not too great between the inlet and discharge of the pipe, you might try hooking a trash pump up to the discharge and back flush the pipe. If there are no air leaks in the pipe, this should also purge the air from the pipe and possibly restart the siphon once the trash pump is removed. If there are air leaks, this also might help you find them by walking the line looking for water seeping from the pipe while the pump is running.