How to Measure a Pool or Spa Filter Cartridge
If your old filter has a faded label, no part number, or has been rebranded under another brand, measuring the cartridge is the most reliable way to find a replacement.
The six measurements that matter
- Overall length: end to end, including the end caps.
- Outside diameter (OD): across the pleated body at its widest point.
- Top end: open, closed, handle, threaded or another style.
- Bottom end: open, closed, threaded, spigot-style or another style.
- Hole opening: the inside diameter of any centre opening, in millimetres.
- Thread or spigot: the outside diameter of any thread or raised spigot, in millimetres.
A cartridge can match on length and diameter but still have the wrong end caps. Always check the top end, bottom end, hole opening and thread or spigot size, and confirm on the product listing before ordering.
Not sure which one? Use our Pool & Spa Filter Cartridge Finder to search by length, diameter, end-cap type, hole size and thread or spigot size.