The first is used as a pump in the larger one with higher water numbers. A waterfall can pass through terraced retaining walls heading down together with a pond at ground height. The water fills up in the well whenever it reaches up to a particular point, the submersible http://tysonhhecy.blogproducer.com/16250899/how-to-easily-replace-a-submersible-water-pump-in-five-steps