Pool Pump Sizing
Swimming pool pumps are available in a wide range of sizes, and are measured in horsepower (listed as HP on the label of your pump motor). If you are replacing your pool pump, and you will continue to use your old pool filter, your new swimming pool pump needs to be the same size (horsepower) as your old pool pump. If you replace your old pool pump with a different size pump,
this new pump may not be the correct size for your old pool filter. This may cause water problems or damage the pool filter. If you will be replacing both your pool pump and your pool filter, please see the Pool Filter Sizing information below.
Pool Filter Sizing
The goal of your swimming pool filtration system is to turnover all of the water in your swimming pool in 8 to 12 hours. This means you will need to know approximately how many gallons of water your swimming pool holds to properly size a swimming pool filter and/or pump. Each manufacturer of swimming pool filters will provide performance data for their pool filters, telling you how many gallons of water each filter model can process in 8 or 12 hours. Most pool equipment dealers will sell pool filter and pool pump combinations, with a pump already matched to the filter. It's as simple as looking at the pool filter performance chart, and selecting the equipment package for your size pool.
If you are purchasing a new pump and filter separate from each other you should first select the correct size filter for your pool. The pool filter manufacturer's performance data will tell you the "design flow rate" of the pool filter, expressed in gallons per minute (GPM). The pool pump manufacturer's performance data will provide you the flow rate of each pump in GPM, and you can simply match the two up to find the correct size pump.