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Choosing the Proper Size Pool Filter: A How to Guide


In order to ensure optimum results from your pool filter, it’s imperative that your filter be the proper size for your pool. But what is the proper size? When determining the size of pool filter you need, you must take into consideration the volume, flow rate, capacity, and the type of filter you need. Moreover, it needs to fit with the equipment sequence you have. Pool filters are available at Westside Wholesale as cartridge pool filter, sand pool filter , and D.E. pool filter .

To begin determining the best type of pool filter for you, you’ll first need to calculate the volume of water that must be filtered. Your pool volume can be calculated by using some basic mathematical equations. The volume of water in a rectangular pool can be calculated by multiplying length x width x depth. For a round (circular) pool, the volume of water can be calculated by multiplying the radius of the pool by the radius of the pool, by the depth of the pool and then multiplying by Pi (3.14). The volume of water in an oval pool can be determined by multiplying ½ of the length x ½ of the width, x Pi, x depth.

The volume of water in your pool is measured in cubic feet, and your pool filter will need to be able to filter that volume of water.

You will also need to determine the capacity of water that your pool will hold. This is not how much water the pool has in volume, but rather the maximum amount of water it can hold. The standard formula for determining capacity requires that you multiply 7.48 x volume. For example if your pool’s volume is 4,500 cubic feet you would multiply 7.48 x 4,500=33,600. In this case, the capacity of your pool is 33,600 gallons.

You will next need to determine the desired flow rate of your pool. Again, flow rate is determined by using a specific formula, and you will need to know it in order to choose the right pool filter size for your needs. The flow rate may be measured in terms of gallons per minute or gallons per hour. Flow rate is loosely defined as the volume of water in your pool that flows past a specific point during a specified period of time.

For example, in keeping with the example of a pool which has a capacity of 33,600 gallons, consider that you want water to “turn over” or be completely filtered every 12 hours. You would simply divide 33,600 by 12 to get a flow rate of 2,800 gallons per hour (gph). If you wanted to know the gallons per minute (gpm) you would divide the gph by 60. So in this case it would be 2,800 ÷60 = 46.67 gallons per minute. In order to select the best pool filter for your needs, you would need a pool filter that can handle that flow.

The last things you’ll need to determine involves deciding whether you want a sand filter, cartridge filter, or a diatomaceous earth (D.E) filter. You may also want to determine if there is a specific brand that you prefer. Westside Wholesale carries pool filters made by the most reputable manufacturers including Pentair, Hayward, Unicel, Jandy, and Nature 2.

It is always a good idea to select an oversize filter (meaning that it can handle greater volumes of water than you actually need) because this will ensure that your desired filter rate is met, and moreover that more debris is captured. In essence, over sizing your pool filter increases the filter’s efficiency.

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