Determining the Proper Size for Your Above Ground Pool Filter

a blue, above ground pool
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Operating the correct sized above ground pool filter in your pool will help you save money and energy. In contrast, choosing one that is too large or too small can cause issues with the entire system. Read on to learn how to calculate the proper size for your above ground pool filter.

Step 1 - Measure the Size of Your Pool

If you have an above ground pool, you will need to measure the diameter and the center depth. Most above ground pools do not have a "deep end" that is substantially deeper than other parts of the pool. You then need to calculate the number of gallons of water in your pool. Do this by multiplying the total volume of your pool times 7.48, the amount of water in a cubic foot of space. For a 24-foot diameter pool with a center depth of 48 inches, the pool holds about 14,000 gallons.

Step 2 - Calculate the Gallons to Be Filtered in Eight Hours

person making calculations with a calculator

An excellent pool filter will clean all the water in the pool in eight hours. This is the minimum rate you want the pump to be able to work at. When we divide 14,000 by eight, we get approximately 1,750. Then divide that answer by 60. This yields the gallons per minute that must be pumped to filter all the water in eight hours. For our 14,000 gallon pool, the gallons per minute minimum is 30.

Step 3 - Determine the Maximum Flow Rate

Different pipe diameters can handle different flow rates. A 1-1/2 inch diameter pipe can carry about 45 gallons of water per minute. This is well above the minimum requirement for a 14,000-gallon pool. Choose a pool filter and pump with 1.5-inch piping, that is rated for a GPM between 30 and 45. Keep the pipeline as straight as possible, with few turns and rises. Most above ground pools use a powerful one horsepower pump and filter system to achieve the desired gallons per minute filtering rate. However, for the pool size in our example, a 3/4 horsepower filter will achieve the GPM rate desired with no problems.

Step 4 - Filter Systems

filling an above ground pool

There are three main filter systems used for both inground and above ground pools: diatomaceous earth (DE), sand, and paper cartridge. Any of these will keep your pool clean. If you desire a filter that has minimal maintenance with maximum performance, invest in a diatomaceous earth or sand filter. You will never have to change, clean or buy cartridges. The only maintenance needed is to backwash the filter, which is described in the filter manual. Choose the largest-capacity filter you can afford that will operate well with the flow rate of your pool. This will ensure the best performance with the least amount of maintenance time.

Step 5 - Install Your Pool Filter

Be sure your pool filter is set on a solid concrete base to reduce vibration. House the electrical system of the pump under a watertight cover to prevent electrocution.

Step 6 - Other Items to Install with Your Pool Filter

For non-cartridge filters, you will need to install a backwash hose, a sight glass pipe, and an air relief valve. Add a pressure gauge to all pumps that measure up to 60 psi. A pressure of 10 psi or more shows the filter needs cleaning.