Expert Help for Choosing the Perfect Filter Cartridge

Filter Cartridge Diagram

Do you need to replace the filter cartridge in your pool or spa? Knowing which replacement model to choose can be confusing. Use the easy step by step guide below to make sure that you choose the correct option!

  1. Measure the outside diameter of the end cap. Be sure to use exact measurement (+ or – 1/32″).
  2. Measure the existing cartridge length. The length is calculated from end cap to end cap and should be exact (+ or – 1/16″). Be sure to exclude any handles or extensions from this measurement.
  3. Measure the top inside diameter. Again, be sure to use exact measurements (+ or – 1/32″).
  4. Do the same with the bottom inside diameter.
  5. Note the name and model of the filter that the cartridge came out of.
  6. Next, you will have to identify the correct top and bottom type. These are the types that you will see. Note the one that most closely matches your filter cartridge.

Open Top/Bottom

Open Top/Bottom w/Gasket

Closed Top

Closed Top
w/ String Handle

Castle Top

Molded Cone


Open Bottom
w/ Male Slip Fitting

Open Bottom
w/ ThreadedFitting

With all of the information that you have now gathered, you are ready to call or visit your pool supply source with the knowledge needed to make an informed purchase!

About Trey Collier

Grew up as a Military Brat. (Thanks Dad. Hats off to my Mom too as it took a special person to be married to someone in the military) Was a competitive swimmer in high school and in college. 11 years a Red Cross Volunteer, teaching kids & adults how to swim. ARC Water Safety Instructor and WSI Trainer, CPR Instructor/Trainer and Advance First Aid Instructor. Proud Dad of two beautiful girls.

Like it? Share It. Leave a Comment or Question below.