Sizing your above ground pool pump is crucial to the overall performance of your swimming pool. An undersized pump lacks the power needed to circulate your water properly to prevent algal blooms. Adversely, a pump that is too large will completely bypass your filter altogether. This, too, creates a dirty pool. In a way, it’s similar to the likes of Goldilocks and The Three Bears. You don’t want a pump that is too big or too small, you want one that is JUST right.
How can you determine which size pump is right? Let’s explore.
What Size Pump Do I Need?
The General Sizing Rule
For the most part, above ground pools are similar in size and shape. Therefore, unlike most inground pools, there aren’t too many extra variables you need to consider when sizing your pool pump. The one thing you need to pay attention to, though, is the maximum gallons per minute (GPM) your pool filter can handle. Your pump’s GPM should never exceed your filter’s GPM. We will show you how to check that later in the blog.
To be honest, sizing the pump is actually pretty straightforward. There is a general rule we use that makes it very easy to pick.
For round above ground pools up to 24 ft. ( pools with less than 15,300 gallons) use a 1 HP pump.
For round above ground pools over 24 ft. (pools with more than 15.300 gallons) use a 1.5 HP pump.
Don’t Know How Many Gallons Are In Your Pool? If you are unsure how many gallons your above ground pool has, review the charts below.
Is My Filter Too Small For My New Pump?
After selecting your pool pump, verify the GPMs of your pool filter. The GPM information is typically listed on the outside label on the filter housing. If unavailable or weathered, you 
can also locate this information in the user manual. If for whatever reason you cannot find your manual, we recommend doing a quick search in our manual database or a Google search. Once you find the manual, print and keep it. I guarantee that you will use it in the future. If it’s an antique of a filter, you may want to call the manufacturer.
Inside the manual, the filter specs typically include the flow rating, filtration area, port size, and turnover rates. The flow rating is essential because it dictates the maximum gallons per minute your filter can handle. In other words, do not go over this number. If your GPMs on the pump exceed the GPMs on your filter, sit back and analyze which one needs to be bigger, the pump, the filter, or both.
Look at the turnover rate listed on the filter. Your pool size should fit within those parameters. If they do not, you should consider purchasing a bigger filter. A properly sized filter is always larger than the gallon size of the pool. You want wriggle room in your filtration area because that way you aren’t backwashing or cleaning your cartridges every week. So, unlike your pool pump, we always recommend oversizing your filter.
Above Ground Pump Resources
Above Ground Pool Pump Buying Guide
Can I Install an Above Ground Pool Pump On an Inground Pool?
Are you still unsure which horsepower you should go with? Or, do you want to discuss replacing just your motor? Feel free to ask a question and join our discussion on our INYO POOLS FORUM.
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