To choose the right spa cartridge, it's essential to check the exact dimensions and ensure it's compatible with your filtration system. Measure the total length, outer diameter, and diameter of the central hole to find an identical or equivalent cartridge. Also, check the type of connection (simple opening, threaded, etc.).
Ideally, check the reference number printed on your old cartridge (model number: Unicel, Pleatco, Filbur, or manufacturer's part number). A properly fitted cartridge ensures optimal filtration, clearer water, and maximum pump performance. If you're unsure which model to choose, always select the one that exactly matches the original dimensions.