Pond Boss Forums POND CONSTRUCTION Building a dam Why did my stand-pipe stop running?

Opening the bottom drain would allow more water pressure at the release point than there was at the top of the spill pipe, since there is more "head" from the pond surface to that lower level. Pressure from only 2 feet of water at the top of the spille pipe; 2 feet plus it looks like about 6 more to the bottom release valve. That's 4 times the pressure - enough to blow a mud plug loose, maybe. As you noted, it would be very interesting to see if the spill pipe worked properly after the water cleared - if not, I would think there must still be some kind of stoppage in the spill pipe's riser section.