Spa Filter Selection Guide

1. Outside Diameter of spa filter end cap. (Plus or minus 1/32")

2. Measure spa filter length.  End cap to end cap. (Plus or minus 1/16")

3. Measure top inside diameter of spa filters.  Use exact measurement. (Plus or minus 1/32")

4. Measure bottom inside diameter of spa filters.  Use exact measurement. (Plus or minus 1/32")

5. Record name and model of the spa filter that the hot tub cartridge came out of.

6. Determine the square footage of your spa filter by reviewing our How To Compute Area (Square Footage) of a Spa Filter page.

7. Identify the type of spa filter or hot tub cartridge top and bottom using the chart below.

Spa Filter Element End Cap Configurations
 

How To Compute the Area
(Square Footage) of a Cartridge

1. Count the number of pleats, and measure the pleat amplitude/height (in inches).
2. Measure the length of the cartridge (in inches) excluding the end caps or any handles or other extensions - the "useable surface area."
3. Multiply the number of pleats by 2, and multiply that number by the pleat amplitude.   Multiply this total by the length of useable surface area, and divide by 144.

For example, a cartridge with 75, 0.625" pleats and a 9-1/4" long useable surface area has an area of 6.02 square feet:

(((75 x 2) x .625) x 9.25) / 144 = 6.02 sq. ft.