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Hot Spring spa filters
11 Hot Spring replacement cartridges from the Unicel 2026 Replacement Guide and Pleatco 2023 catalog. Model-year fitment is not published in these sources, so find your cartridge by its OEM part number (printed on the end cap) or by measuring it.
| OEM | Unicel | Pleatco | Size | Status |
|---|---|---|---|---|
| 31382 (formerly 31116) | 4CH-35 | — | 4-5/8" × 16" | unverified |
| 303279 | 5CH-37 | PFF42TC-P4 | 5-5/16" × 9" | cited |
| 33521 | C-4326 | PRB25-IN | 4-15/16" × 13-5/16" | cited |
| 31233 | C-5431 | — | 5-1/8" × 10-1/4" | unverified |
| 31489; 71825; 71826 | C-6330 | PWK30 | 6" × 10-1/2" | cited |
| 31489; 71825; 71826 | C-6430 | PWK30-4 | 6" × 10-1/2" | cited |
| 1642301-1; 78161 | C-6350 | — | 6" × 14" | unverified |
| 1642301-1; 78161 | C-6355 | — | 6" × 14" | unverified |
| 31250 | C-6433 | — | 6" × 9" | unverified |
| 31115 | C-6600 | — | 6-3/8" × 11-7/8" | unverified |
| 31114; 71827; 71828 | C-8465 | PWK65 | 8-1/2" × 10-1/2" | cited |