Filter Measurement Tips
The Diameter (width) of your hot tub filter cartridge is measured from one outside edge to the other outside edge at the widest part of the filter. Measure the diameter down to the nearest 1/16".
The Length of your hot tub filter is measured from the outside edge of one end cap to the outside edge of the other end cap.
In open end hot tub filters (type 1), you can measure the hole diameter(s). Don't include any tapering or pinholes in your measurements.
With slotted hole end caps, measure the diameter of the hole without the slots. Most slotted holes are 1 7/8" or 2 3/8" in diameter.
Important Note: While you should take these measurements as accurately as possible, you can also take them with a grain of salt. The measurements on old hot tub filters may not match the new filter measurements on Find-My-Filter due to expansion, contraction and wear of the old one. You could easily be off by 1/16th to 1/8th inch. Be prepared to adjust your Find-My-Filter measurement input slightly if you aren't getting a listing that looks right to you.
There are two types of threaded ends skinny (normal) and fat (SAE). If your filter has a threaded end, be sure to take note of which kind you have.
- If you have a digital camera, you may wish to take pictures of the end caps while at your hot tub. That will allow you to refer to the image when selecting the correct replacement for your hot tub at the computer.
- Disregard any color discrepancies between the original and the replacement. Different hot tub filter manufacturers use different colors of plastic. As long as the measurements are as close as you can get to accurate and the ends match, you should be able to choose the right filter for your hot tub.
- In some instances, there are two listings for what looks like identical hot tub filter cartridges. The measurements will be the same, the end caps look this same but there is a difference in "SF." This refers to the square footage of the "media" (the white stuff in the center of the hot tub filter). Typically, hot tub replacement filters with a higher SF will last longer and catch more debris. However, both filters will function normally in your hot tub.