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Hot Spring OEM 31489 spa filter (C-6430)
Listed for: Hot Spring (Watkins)
Fits Hot Spring OEM 31489, 71825, 71826 cited
Ø 6"L 10-1/2"30 sq ft| Unicel | C-6430 |
|---|---|
| Pleatco | PWK30-4 |
| Filbur | not sourced |
| Top | 1-15/16" / open |
| Bottom | 1-15/16" / open |
Retailer search links — see disclosure. Verify dimensions before ordering.
Source note: 4 oz media; Unicel: model dated after 1990
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 6" in diameter and 10-1/2" 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. Unicel C-6430 and Pleatco PWK30-4 are cross-referenced to each other in the Pleatco 2023 catalog, so either should fit the same housing. Hot Spring has used 3 OEM numbers for this cartridge; any of them should map to the same replacement.
Similar-diameter Hot Spring cartridges
- C-6330 cartridge (OEM 31489) — 6" × 10-1/2"
- C-6350 cartridge (OEM 1642301-1) — 6" × 14"
- C-6355 cartridge (OEM 1642301-1) — 6" × 14"
- C-6433 cartridge (OEM 31250) — 6" × 9"
Sources
- Unicel 2026 Replacement Guide — OEM Cross Reference, PDF p.38; spec table PDF p.11 (PDF)
- Pleatco 2023 Catalog — Unicel-to-Pleatco cross reference, PDF p.43 (PDF)
Not in sources: no Filbur equivalent sourced; no model-year range in source.