Pool pumps for above ground pools fall into several different categories. What are the different categories for pool pumps, and what are the strengths and weaknesses for each type of pool pump?
Number of Speeds
Pool pumps can be divided by the number of speeds it can run, whether one, two or variable. What are the pros and cons of each of these types of pumps?
Single Speed Pumps
Single speed pumps are the classic design, running at the same speed once you turn them on unless they are wearing out or there are mechanical problems. Single speed problems have many points in their favor. They’ve existed for decades. They are the least expensive units because of their simplicity. They tend to be noisier than pumps that adjust their speed to the demands of the pool that sometimes slow down. These pumps can be more expensive in terms of the electricity they consume, if they run constantly, including at a speed higher than what the pool actually needs. Depending on the size of the pump and how often you run it, these pumps can use several thousand dollars of electricity a year.
Single speed pumps are the best choice if you need a high powered pump to run a filter, skimmer and other pool equipment for the short season the pool is open. This makes single speed pumps the perfect above ground pool pump if you’re only going to use the pool for three to four months in the summer.
Two Speed Pumps
Two speed pumps use an induction style motor. They can flip between an efficient low speed or less efficient high speed when power is necessary. These pool pumps cost more than single speed pumps but less than variable speed pumps. They use less power than single speed pumps unless your pool needs the high speed mode most of the time. One popular way of saving on power with these pumps is running them on low power all the time unless you have to turn it on high power to vacuum a pool, to drive a skimmer and pool vacuum simultaneously (though this only matters if they rely on water flow to operate) or running a pool heater that needs the faster flow to actually make a difference in heating your pool.
Variable Speed Pumps
Variable sped pumps use a permanent magnet motor. These are the most expensive of these three pool pump types. They let you set an exact flow rate, so you can adjust the water flow to the pool’s needs. It is more energy efficient than a two speed pump when the high setting is more than the unit needs. In general, slower is better, and energy efficiency means as slow as you can go without the pool skimmer and vacuum stopping.
Another point in favor of the variable speed pump is how quiet the motor is, regardless of its speed.
Variable speed pumps are the most cost effective choice if you are constantly varying the load on the pump, such as running the basic filtration throughout the year, middling speed for a pool heater or skimmer and top speed when running a pool cleaner and pool heater simultaneously. The energy savings these models provide make them the better choice if you run the pump year round but don’t always need it on the highest setting.
The variable speed pump is the best above ground pool pump for an above ground pool used year round, and nearly everything in the pool but the swimmers powered by it.
Horsepower
Another ranking system for pool pumps is the horsepower they generate. Your pool pump must have the necessary horsepower to generate the gallons per minute flow rate the unit needs for basic water circulation, and more power is necessary if you will run equipment like skimmers off of the pool pump’s flow.
One word of warning is that higher horsepower pumps are not necessarily more energy efficient. And not all pool pumps with the same horsepower generate the same amount of water flow you need. However, a pump without enough power for the job will wear out faster than a properly sized one.
Gallons Per Minute
Pools should have a turnover time of eight to ten hours. This is how long it would take for the average water particle to be re-filtered and re-treated by the pump. The ideal gallons per minute, or GPM, flow rate for the pump is the pool size in gallons derived by the turnover time in minutes. In the case of an 8 hour turnover time, device the volume of the pool in gallons by 480 to get the minimum flow rate from the pump.
The gallons per minute rate is given for most pool pumps, though others give that value as gallons per hour. Convert GPH to GPM by dividing by 60.
When selecting a pool pump, a pool pump must have the GPM rating your pool needs for its desired pool turnover time as a minimum. Higher GPM is better.
Determining Whether the Pool Motor your Looking at is What you Need
Let’s suppose you’re in the store looking at pool motors. How can you tell what the motor is? Look at the nameplate or sticker on the surface. This says who made the unit, provides a voltage rating, horsepower, Hertz rating and service factor. Most pool pumps list their gallons per minute or gallons per hour capacity as well. If the pool pump’s nameplate doesn’t specifically state that it is a single speed or variable speed motor, you can still use the model number to look up that information.
The actual total horsepower or effective horsepower is the horsepower on the motor multiplied by the service factor. If it says the motor puts out 1.5 horsepower and has a service factor of two, the motor is actually a two horsepower motor.
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