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31CARTRIDGE-T35 spa filter equivalents
Part number 31CARTRIDGE-T35 appears in 1 cross-reference row below. Each row lists the OEM, Unicel and Pleatco numbers that the source documents treat as interchangeable, plus the cartridge size so you can confirm against your old filter.
The same numbers, on one page, are in the cross-reference lookup. A schedule for this part number, and the buy link, are on the replacement schedule and reorder page. Published intervals by brand are in the replace and clean calculator.
Nordic Hot Tubs 4CH-935 cartridge, 4-15/16" (125 mm) × 9-1/4" (235 mm), 35 sq ft. Unicel 4CH-935, Pleatco PWW35L.
Unicel 4CH-935
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| OEM | CARTRIDGE-T35 |
|---|---|
| Unicel | 4CH-935 |
| Pleatco | PWW35L |
| Filbur | not listed |
| Size | 4-15/16" (125 mm) × 9-1/4" (235 mm), 35 sq ft |
Sources
- Unicel 2026 Replacement Guide: OEM cross reference (Nordic Hot Tubs section), PDF p.46 (printed p.42); spec table PDF p.8 (printed p.4) (PDF)
- Pleatco 2023 Catalog: Unicel-to-Pleatco cross reference, PDF p.47 (4CH-935 = PWW35L) (PDF)
- Nordic Hot Tubs filter chart (2023): CARTRIDGE-T35 row: Unicel 4CH-935, Pleatco PWW35L, Filbur NA, Waterway 817-4035; model list (PDF)
- Nordic Hot Tubs owner's manual (01.2024): Filter Quick Reference by Model, p.22: CARTRIDGE-T35, 9-1/4" x 4-15/16", handle top, 2" SAE female thread, 35 sq ft (PDF)
Not in sources: no Filbur equivalent (Nordic's chart prints NA); Pleatco's spec table prints PWW35L as 5" x 8-1/2" with a 1-1/2" bottom, not 4-15/16" x 9-1/4"; Nordic's chart has no Crown entry for 2008-2014.
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