Things to know about filters

Selecting a good filtration system is the key to healthy, clean, and sparkling water. Whether you're replacing an old filter or installing a filter on a newly built pool, you'll need to match the filter to the pump and the size of the pool.  Here is a three step method to getting the right filter for your pool

First calculate the volume -- number of gallons in your pool.

Take the length, width and depth of your pool and multiply it by 7.48 (there are 7.48 gallons of water in every square foot of your pool. If you have a circular pool multiply the radius by 3.4(pi) by the average depth. This is an example based on a pool that is 36 by 18 and 5 feet deep. The total volume of water would be 36 x 18 x 5 x 7.48= 24,235 gallons of water.

Then calculate the flow rate: The flow rate is the volume of water flowing past a given point during a specific period. In order to get the right filter, you need to know that your flow rate is high enough to filter your pool volume. Since this will be based on how long your run your filter - you need to calculate this volume based on that run time. For the pool size in our example, if you are going to run your filter 8 hours a day, the hourly flow rate would need to be (24,235 gallons/8 hours) 50.48 gallons per minute.

Then calculate the filter flow rate: Most filters give you a sq. ft. rating. For example if the filter area is 4 sq. ft. and the filter rate is 12.8 gallons per minute then your filter flow rate is (4 x 12.8) 51.2 gallons per minute. That would meet our requirement of 50.48 gallons per minute.

A final word of advice. A bigger filter will make it easier to get the job done. In fact if you look at the total cost of ownership having a bigger filter will let your run it less time and save you energy cost. The important thing is that you do not undersize your filter.