When replacing a fountain pump or choosing a new one, first there are some key terms to keep in mind:
"Head": This is the maximum vertical lift of the pump. For example, a 6' head means the pump is rated to pump water up to 6 feet high. Note, however, that at 6 feet the pump would be providing very little water, with gallons per hour around zero. So if you need to pump, say, 200 gph at 72", you will probably need about a 300-600 gallon per hour pump to do the job. See a "pump curve" for the amount of water pumped to various heights.Major pump manufacturers include pump curves on their boxes, brochures, or other literature. You should take a good look.
"GPH": Gallons per hour, usually rated at different heights
"GPM": Gallons per minute, usually rated at different heights
"Pump Curve": The amount of water volume "curved" according to various heights. A 500 gallon per hour pump, for instance, might pump 500 gallons per hour at 0" lift, 350 gallons per hour at 24" of lift, and so forth. When buying a pump for the first time or when seeking a replacement pump, it is essential that you know how many gallons per hour you want to pump and at what heighth (head).
Water Volume: The total volume that you will be pumping is controlled by a few factors. One factor is the size of the pump, as covered above. But you also must consider how wide your tubing will be. Tubing is measured in two ways: inside diameter (i.d.) and outside diameter (o.d.). Very skinny i.d. tubing will greatly reduce water flow. Many customers are shocked when they find that, after hooking up their 500 gallon per hour pump to ½" inside diameter tubing, they are only getting what they consider a trickle. Well, about the most they will get is 200 gallons per hour or so under the very best conditions. They have restricted the flow too much by choosing skinny tubing. When purchasing a pump, find out what size of tubing is supposed to go with it. Another problem is running the tubing too far. Long lengths of tubing create resistance. If your pump calls for ½" i.d. tubing, for instance, but you are running the tubing twenty feet from the pump, it is a good idea to use ¾" tubing instead so as not to cut down too much on flow.
How much water do I need? What size of pump?
This question is answered in part by whether you want a "trickle" or a roar. When you buy a fountain, you will usually find a recommended flow. For waterfalls, use this as a rule of thumb: for every inch of stream width or waterfall "sheet," you will need to deliver 100 gallons per hour at the height you're pumping. So if you are building a 12" wide waterfall that is three feet tall, you need to buy a pump that will be pumping 1200 gallons per hour at three feet of height.
For ponds, whenever possible, it is a good idea to recirculate the water once an hour, more often if possible. Thus, if your pond is 500 gallons, try to buy a pump that will recirculate water at a rate of 500 gallons per hour. For really large ponds, this is not necessary and is far too expensive.
For a nice waterfall effect, we usually advise about 4000 gallons per hour or more at the top of the waterfall. This creates enough volume for a wide, crashing spill. Adjust stones to soften the splash if desired.
When Is an External Pump Appropriate?
"In-line" pumps provide the "most bang for the buck" in two ways. For one, the purchase price is quite reasonable for the high volume of water being pumped. But even more importantly, these pumps dramatically outperform typical submersible pumps, cutting electrical costs two to three times. Since electrical costs for a large pond can easily run from thirty to one hundred dollars a month, choosing the most energy-efficient pump is tremendously important.
However, if you need a lot of "head," that is, if you are pumping to a height of more than say, seven or eight feet, or if you must pull the water (not "push", for in-line pumps push water fine but don't pull well) a long distance from the pond to a skimmer located far away, then these pumps probably won't work for you.
How About Battery-Operated Fountain Pumps?
We receive many, many calls about battery-operated pumps. While there are companies who manufacture pumps that can operate on "A" and "AA" batteries, we have not found a battery-operated pump that lasts or that is reasonably priced. For those customers who need battery fountains for wedding centerpieces (a common request), we suggest finding the one you want and buying as many as possible at a store like Wal-Mart. You get the whole fountain for as good of a price as we could get you these specialized pumps all by themselves!
Where is the Pump Made?
Pumps, like anything else, are made all over the world, and we suggest you buy pumps from someone who will stand by a guarantee and who has testing programs before marketing their pumps. It used to be that Asian pumps were quite bad but this is changing. What matters most is how well the pumps have been engineered and the materials used in the production. Italy for quite a while has been the major manufacturer of fountain pumps (think of how long Italians have had fountains), but Germany, Korea, Taiwan, and China are making pumps as well. Most American fountain pump companies (for example, Cal Pumps and Beckett) have their pumps manufactured overseas. As long as American engineering is used and the plans are followed, this should not be a problem.
Should my Pump Have a 2-wire plug or a 3-wire plug?
Outdoor pumps should always use a grounded, 3-wire plug. Indoor fountains sometimes have 2-wire and sometimes 3-wire plugs. For people wanting a really thin cord, 2-wire pumps provide the more aesthetic experience. Some retail stores require 3-wire pumps even for indoor fountains (though, ironically, they might not for aquarium pumps), and these thicker cords can be hidden by plants, stones, or other decorations. All pumps must be connected to a GFI outlet for safety.
Why do pumps burn out so often?
95% of the time the customer has let the pumps get hot by running them dry. Most fountain pumps are water-cooled and once the fountain is dry they burn up. Usually there is nothing you can do about this other than to buy a new pump. Also, however, pumps are supposed to be cleaned every so often by opening up the impeller case on the fountain pump. Follow the manufacturer's directions.
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