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Pond Pumps

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The pump is one of the most important pieces of equipment in a well-functioning ecosystem pond. It needs to be reliable enough to stay on 24 hours a day, 7 days a week, without having problems or needing rest. On top of that, it needs to be efficient, so that the electricity costs to run the pump remain reasonable.
Choosing a pump happens to be one place that people often go wrong, picking an incorrectly- sized pump, a pump that’s unreliable, or a pump that’s an energy hog. Often people will try to save some money up front when choosing a pump, but it’s usually a mistake since the running costs of a pump over time can far exceed its initial purchase price. The most important features of a pump are reliability and efficiency. We’ll delve into this further in a bit,but first, let’s start with the two main types of pumps available:



1) Submersible Pumps

Submersible pumps are actually placed inside of the pond, below the surface of the water, usually inside of a skimmer. This is traditionally the most popular method of plumbing decorative ponds, mainly because of ease of installation. Just plop the pump in water and turn it on with no priming necessary. However, what submersible pumps make up for in simplicity, they lose in efficiency. A good external pump (which we’ll talk about next) can often pump the same amount of water as a submersible pump but will use less electricity doing it.

Submersible pumps are available in two types: magnetic drive and direct drive. The main difference is a direct drive pump uses a drive shaft that is directly connected to the motor to turn the impeller (the part that moves the water). A magnetic drive pump uses magnets instead, so the impeller and the motor aren’t actually connected with a physical drive shaft. The main selling point of magnetic drive pumps is that the motor is fully enclosed, so no motor oil could possibly leak into the pond water. Direct drive pumps make use of gaskets and seals to stop fluids from leaking, much like a car engine uses gaskets and seals to keep oil on the inside. You’ll likely find that direct drive submersibles are available in larger, more powerful pumps, with magnetic drive pumps being slightly less powerful. Magnetic drive pumps will also lose their power more quickly as the head pressure of the pumping system increases. We’ll talk more about head pressure in the next chapter.



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2) External Pumps

In contrast to submersible pumps, which sit “inside” the pond, external pumps sit outside the pond on dry land. In the past, people would mainly use an external pump in higher volume situations, since external pumps are usually available in larger sizes than submersibles. Lately, however, more and more people are using high-efficiency external pumps, since they often use less power than a similarly sized submersible. We can’t stress enough how important an efficient pump is! External pumps are usually a little more expensive to purchase initially, but given the energy savings, the money can easily be made back over time. We’ll offer some examples later to better illustrate the savings. The one thing to keep in mind with external pumps is that they must be “primed” before they can start pumping water. This just means that there must be water in the pump and in the lines before it can be turned on. Some of the newer externals are “self-priming,” which make them a little easier to use.




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Self-Priming External Pumps

The term “self-priming” is slightly misleading. To somebody who doesn’t know any better, it sounds like the pump doesn’t need to be primed at all. In reality, “self priming” means that the pump can begin operation with the pump and line only partially filled with water. Where a normal pump won’t work very well or at all if there’s any air in the system, a self-priming pump will still work if there’s some air in the system. In the initial stages of operation, the pump will work to get rid of the air as part of the self-priming process. A self-priming pump still needs some water to work, however. It won’t work at all if there’s no water in the pump or lines.



Flood Suction

The easiest way to ensure successful priming with an external pump is to install the pump in a “flooded suction” configuration. This just means that the pump is lower in elevation than the surface of the pond, so that water naturally flows through the pipe to the pump via gravity.






Check Valves

It’s possible to install the pump above the surface of the pond in elevation, but it just requires an extra step before turning on the pump. You will need to install a check valve in the PVC pipe below the water level. A check valve is a PVC fitting that only allows water to travel one way through the fitting. If the water tries to travel the opposite direction, the valve will close and not allow water through. The idea with a check valve is to only allow water to flow from the pond to the pump , and not the other way around. That way, before you turn on the pump, you can pour water into the pump to fill up the pump and pipe, and it won’t leak back into the pond because of the check valve. When you turn on the pump then, it will have water in the pump and pipes, ready to go.






Submersible or External?

As we mentioned earlier, submersible pumps are popular because they’re easy to install. Just put one in a skimmer and hook up a PVC pipe, and you’re ready to start pumping water. For many smaller ponds, an energy-efficient submersible pump is an excellent option. That being said, some of the newer external pumps have some very convincing benefits.


Here are a few:

1) Energy Efficiency. Many people forget to calculate the electricity costs of running a pond. The pump needs to run 24 hours a day, 7 days a week, and the electricity costs can really add up. Even if a pump costs less to purchase, you can easily make it back in electricity costs if the pump is more energy efficient. We’ll see some real-world examples below.
2) Reliability. It’s not uncommon for a quality external pump to have a life expectancy double that of a comparable submersible pump.
3) Maintainability. If you do have a problem with an external pump, many of the good brands, including the Sequence pumps we carry, allow parts like motors and impellers to be rebuilt and/or replaced without having to buy a whole new pump.
4) Low Noise Level. External pumps were traditionally noisier than submersible pumps, which was a turn-off for many people. This has changed in recent years. The external pumps that we recommend and sell are very quiet.

The one downside to external pumps is that you need to find a place to hide them in your landscape. In most cases, this isn’t a big deal. You can dig a small pit behind some rocks or shrubs to place equipment or place the equipment next to a house where it’s out of the way. Overall, if you’re building a medium to large-sized pond, we’d say the benefits of going external outweigh the couple minor inconveniences.

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Comparing Pumps for Electricity Costs

It’s actually quite easy to figure out how much money a given pump will cost to run each month. The important number in the pump specs is the Watts. Just like a 100 Watt light bulb will use more power than a 60 Watt, a 500 Watt pump will use twice as much power as a 250 Watt pump.
To figure out the actual running cost, you’ll need to look at your electricity bill to see how much you pay per kilowatt hour in your area. This number could be anywhere from $0.08 to $0.35, depending on where you live. If you live in Hawaii, where that cost is closer to $0.35, you will likely be paying 3 times more for electricity than if you live in Oregon, for example. So a $33/month pump in Oregon could cost around $100/month in Hawaii! The average electricity cost in the United States in 2012 was $0.12/Kwh, so we’ll use this number for our calculations below. If you’d like to see a chart of all the various electricity costs in the USA, please see the following link:
USA Electricity Costs: http://www.eia.gov/electricity/monthly/epm_table_grapher.cfm? t=epmt_5_6_a



Calculating the Running Cost of a Pump

Using our “Pump Electrical Cost Wizard” at the below link, simply type in the wattage of the pump and the cost per kilowatt-hour you pay in your area. Make sure to input “24” as the hours of use each day. For example, if we use the average cost of $0.12/Kwh, a 250 Watt pump will cost about $21 per month to operate full time.


Pump Electrical Cost Wizard


Now that we know how to calculate the running cost of a pump, we can start looking at which pumps are going to save us money. Please note that we talk a little bit about “head pressure” here. The next chapter will delve into head pressure in much more detail, but for now, just keep in mind that head pressure is the resistance the pump must overcome to pump water. For example, a 5’ high waterfall will add 5’ of head pressure. Let’s take the following pond as an example:



Choosing a Pump Example 1: 4,000-gallon pond requiring 4000gphat 10’ of head pressure for a large waterfall

Let’s have a look at three different pump options to see how they compare efficiency-wise:



External Pump - Sequence 4K 5800

  • 4200 gph @ 10’ of head

  • 296 Watts

  • $25.57/month to operate (at $0.12/Kwh)



Direct Drive Submersible Pump - ShinMaywa 5700

  • 4200 gph @ 10’ of head

  • 567 Watts

  • $48.99/month to operate



Magnetic Drive Submersible Pump - Alpine Cyclone 6550

  • 4132 gph @ 10’ of head

  • 500 Watts

  • $43.20/month to operate

As you can see from looking at the running costs of each of the 3 options, the most efficient pump by far is the Sequence external pump. The magnetic drive submersible came in second place. For a pond of this size, you can still get away with using a magnetic drive pump since the head pressure is only 10’, but if the head was increased to, say, 20’ instead of 10’, the magnetic drive pump wouldn’t be able to keep up. The ShinMaywa direct drive submersible pump is a very high-quality pump—it has all stainless steel housing and is likely to be more reliable over time.
Let’s say for a moment it came down to choosing either the Sequence or the ShinMaywa. If you look at running costs, you’ll see that going for the external pump will save about $23 per month in electricity costs.
If you add up the costs for a few years of use, saving $23/month adds up to a $828 savings. The Sequence will likely cost more upfront since it is a higher quality, longer-lasting pump, but as you can see, you can recoup your money over time quite easily.

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Example 2: Small 1,500-gallon pond requiring 1500 gph at 5’ of head

At smaller flow rates like this, external pumps will often be too large, as will the direct-drive submersibles. The best choice at smaller flow rates like this and lower head pressure is to use an energy-efficient magnetic drive pump like the Alpine 2100, which will pump 1500 gph at 5’ of head using 190 Watts ($16.42/month to operate at $0.12/Kwh). If we moved the head pressure up to 10’ or 15’, however, and still required 1500 gph, we’d now be getting back into the direct drive submersible, or possibly an external pump.

Need help choosing pond equipment?

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<< prev: 2.3 Plumbing & Pipes for your pond: next: 2.5 Pond Rocks & Gravel >>

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