What Size Pump Does My Water Feature Need?
Can be daunting. There are submersible pumps, garbage pumps, centrifugal pumps, self-priming pumps, magnetic drive pumps, and the list goes on. I am going to keep this post simple though. I won't go into pro's and con's for all the different kinds of pumps. I am just going to tell you how Ross NW Watergardens picks a pond pump when we build a water feature.
Step 1: What Kind of Water Feature?
The pump you choose is directly related the type of water feature you have or are designing. Will your pond have fish in it?
If so then you probably want a centrifugal pump. Why are centrifugal pumps better for koi ponds? Centrifugal or in-line pumps sit outside the pond. They give you the ability to use one pump and integrate several filtration methods.
For example, an in-line pond pump can be plumbed so that it draws water from a skimmer, a bottom sand filter, and a bog filter. It is more difficult and less effective to set up multiple filtration methods with a submersible pump.
Centrifugal pumps have an expected life span of 10-15 years and tend to be very reliable. You can go out of town and feel comfortable that your mature koi will have the water circulation they need.
But if your pond will not have fish? Then a submersible pump may be the answer. The pump can sit in your skimmer or a vault in the pond. Plumbing is simple and the initial cost is much lower.
A submersible pump can be expected to last 4-7 years. Be sure to get a true pond pump. Many landscapers install sump or garbage pumps in ponds. The initial cost is low, but the long term costs are high. Why?
A garbage pump is designed to be used for short periods of time and then be shut off. Pond pumps are usually for many hours, days, or even months at a time!
Garbage pumps are also extremely inefficient, using a lot of electricity to move water. A typical 4000 GPH sump pump will require 10-11 amps. A comparable pond pump will use 2-5 amps. The difference means several hundred dollars a year to a Portland pond owner.
How can you be sure to get the right kind of submersible pump? The key is to specifically request a "continuous duty" pump.
Step 2: How Big is the Water Feature?
If your water feature is very large, then you might consider a centrifugal pump even if you won't have fish or a lot of filtration. Why?
While submersible pumps have become much more efficient recently, in-line pumps generally use less electricity. So if you need a high volume pump, or even multiple pumps, then a centrifugal pump may cost less in the long run. If you will be using over 10,000 GPH give this a lot of thought.
Regardless of the size of your water feature or kind of pump chosen, you need to decide how much water flow you need.
This is a little tough. I just know, from experience, what size pump a certain size stream and pond need. But that doesn't help much does it? This online tool, though, works really well. I use it sometimes just to check myself before I order a pump.
Step 3: Choose Your Brand and Model of Pond Pump.
How can you choose a pond pump when there are dozens of choices that are the size you need? Here are a couple things to consider:
- How much will it cost to run this pump? Compare "amps" required by different pumps. The lower the number, the lower the cost.
- How long is the warranty? Three year warranties are fairly common, but some pumps offer 5, or even 6 year warranties.
- What is the reputation of the brand? Do a search for "[pump brand] reviews. Search the water features forum at lawnsite.com. No mention of the pump you are considering? It probably has not been around long enough to have a reputation.
- How much does the pond pump cost? A 4000 GPH pump will cost between $180 and $700. Why such a wide range? Efficient pumps from reliable manufacturers with long warranties will cost more.
That's the basic process I go through to pick a pump for one of my clients. Still have questions?
Quick Water Feature Pump Tips:
- Centrifugal or in-line pumps sit out of the water and are more efficient and long lasting than submersible pumps.
- Submersible pumps should be continuous duty.
- This is a very popular pump. It is not continuous duty- don't install it in your pond!
- Want to figure the cost of running your pump? Use the calculator on this page.