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Hot Spring OEM 31233 spa filter (C-5431)
Listed for: Hot Spring (Watkins) — unverified
Fits Hot Spring OEM 31233 unverified
Ø 5-1/8"L 10-1/4"30 sq ft| Unicel | C-5431 |
|---|---|
| Pleatco | not found in source |
| Filbur | not sourced |
| Top | 1-15/16" / open |
| Bottom | 1-15/16" / open |
Retailer search links — see disclosure. Verify dimensions before ordering.
Source note: Unicel spec: Model FH/IH (220 volt)
How to confirm this is your filter
Pull your current cartridge and measure it end to end, including any handle, and across the widest point of the pleats. This cartridge measures 5-1/8" in diameter and 10-1/4" long, with a 1-15/16" / open on top and a 1-15/16" / open on the bottom. The bottom fitting matters most: a cartridge with the right diameter but the wrong thread or open-end size will not seal in the filter housing, letting unfiltered water bypass the media.
The 30 sq ft rating describes the pleated media area. Hot Spring housings are designed around a particular cartridge, so choose a replacement with the same size and fittings rather than a larger area rating. We did not find a Pleatco equivalent for C-5431 in the Pleatco 2023 cross-reference, so search by the Unicel or OEM number.
Similar-diameter Hot Spring cartridges
- 5CH-37 cartridge (OEM 303279) — 5-5/16" × 9"
- C-4326 cartridge (OEM 33521) — 4-15/16" × 13-5/16"
⚠ Unverified / possible conflict: this row has not been fully confirmed against a second source. Gaps: no Pleatco equivalent found in Pleatco 2023 xref p.43; no Filbur equivalent sourced; no model-year range in source. Measure your old cartridge before ordering.
Sources
- Unicel 2026 Replacement Guide — OEM Cross Reference, PDF p.38; spec table PDF p.9 (PDF)