External and submersible Pumps are available in external and submersible models, and each of the pumps has whirling palms that pressurize the water and push it into a motion. Submersible pumps are easier to use than external, but more expensive. They are easy to install, they start without priming, and most importantly, they work quietly.   Before buying a pump for your waterfall, check its electric rating. Large waterfall request powerful pump, so it consumes more electrical energy. Choose a magnetic-driven pump, which use less energy than direct- driven. Usually, the most efficient pumps are the most expensive, but they can pay for themselves in energy saving.   Size The most important parameter when choosing pump is to buy it in the right size. Manufacturers rate electrical power in amps or watts, but the critical measure is the number of gallons of water it will pump per hour (gph) to a height, called the head. To properly choose the size of your pump first, you should calculate the capacity of water in the waterfall. Usually, the pump for waterfalls should be able to turn over the total volume of water in an hour.   If you doubt, buy a more powerful pump. You can reduce flo more...