How to Measure your Hot Tub Filter

Use these instructions to measure your hot tub filter.

1. Measure the outside diameter of the cartridge (in inches, +/- 1/32").
    
2. Measure the cartridge length including end caps, but excluding any handles or other extensions. Measure through the centre if possible (in inches, +/- 1/16").
    
3. Use the Filter End Cap Chart to identify your cartridge end cap configuration. If the top and/or bottom is "open," measure the inside diameter (in inches, +/- 1/32").