Well the people who sold you the pump wher mis informed about that pump as well. Torpedo pumps are generally used on waterfatures that are long and tall. Meaning it needs highhead pressure to even function properly thats the reason they fail so often. I wont even use them unless i have a min of 15-20' of head preesure. Looking at your waterfall your probably more around 6500 gallons plus. A 10000 gallon would be cooking a lot faster and more intensly. Right now you by u using a 2" hose your basicaly trying to squeeze all that water through a straw and by doing so creating friction loss and hurting your pump causing it to fail. Go to a 3" line. I can go into charts of dynamic head presure and friction loss but I think you get the point. If you want info i can give you charts. As for a pump are you looking more for energy efficient pumps? Your hose length is small and height is low you can go to a hydrive pump. Its a combo magnate and direct drive pump. Anjon makes one its 10000gallon monsoon pump.
Turner Landscaping, LLC