A pump is the most critical feature of a water garden because it not only keeps water moving (to detract mosquito infestations), but more importantly, moving water looks pleasant and is one of the most appealing aspects of a pond.
Nowadays, most reliable pumps are magnetic-driven and can consume as little energy as a 60W light bulb. Our advice is to always choose the magnetic-driven pumps over the direct drive pumps. Magnetic-driven pumps are designed for continuous pond pumping, are quieter, and are more reliable than the direct-drive pumps. The next biggest question that many potential pond owners have is: “What kind of pump do I need?"
The answer to this question varies, as everyone has different requirements when it comes to pond pumps. Pumps are sized by gallons per hour (GPH) output at one foot of lift or height. Manufacturers usually offer charts that break down the power of each size pump according to incremental heights of one foot. For example, Algreen Products provides pond pump sizing charts that can be referenced online. It is recommended that you circulate your body of water at least once every 2 hours. Therefore you will need to size your pump to ensure that it has half the GPH rating as the volume of your pond in gallons. For example, if you have a 1000 gallon water feature, you will require at least a 500 GPH pump.
However, pond owners with waterfalls or aquatic life will require significantly more pumping power. Calculating the proper pump for waterfalls is a bit trickier, because you must estimate your waterfall's height. To do so, you must measure the vertical height from the top of your pump to the top of your waterfall. In addition, you must add another foot of height or lift for every 10 feet of hosing you will be using (this will allow for loss of volume from resistance within the hose). To calculate the required pump GPH, a general rule of thumb is that each inch of width of the channel will require an extra 100 GPH. For example, if your stream or waterfall spillway will be 10 inches wide, you will need a pump that produces an excess flow of 1000 GPH at your waterfall's height. Here's a tip to help you out: One high-end waterfall pump that we strongly recommend is the MaxFlo series of waterfall pumps.
Pond owners with fish will have to worry about the increased pump power required to both oxygenate the water for the fish, and to drive the filtration devices that will keep the pond water free of ammonia, to allow your fish to survive. The general rule of thumb is that you must double your pump GPH if you plan on raising fish. An example of a pump that would be appropriate for fish and aquatic life is GardenSuperMart's UltraFlo line of pumps. These pumps have oxygen intake valves and an unique air/water air mix system which effectively increases the oxygen concentration in your pond.
Before you spend money on a pond pump, make sure you do your preliminary research. Ensure that you're investing in a high-quality pump with the right specifications, and you will enjoy your water feature for many years to come.