Pleatco PWK30 = Unicel C-6330 = Filbur FC-3915
30 sq ft hot tub filter, 5-7/8" diameter × 10-1/2" long. Top: 1-15/16" open · Bottom: 1-15/16" open. Pleatco application: Watkins Hot Spring Spas.
Interchangeable cartridges
- Unicel C-6330 confirmed by: Pleatco p.47 (Unicel to Pleatco cross reference) Unicel p.12 (Cartridges by series (dimensional listing))
- Filbur FC-3915 confirmed by: Pleatco p.48 (Filbur to Pleatco cross reference) Filbur p.10 (Dimensional cartridge listing)
Published dimensions, side by side
Each manufacturer measures a little differently. Compare these with your old cartridge.
| As published by | Pleatco PWK30 source | Unicel C-6330 source | Filbur FC-3915 source |
|---|---|---|---|
| Outside diameter | 5-7/8" | 6" | 6" |
| Length | 10-1/2" | 10-1/2" | 10-1/2" |
| Top end | 1-15/16" open | 1-15/16" / open | 1-15/16" open |
| Bottom end | 1-15/16" open | 1-15/16" / open | 1-15/16" open |
| Filter area | 30 sq ft | 30 sq ft | 30 sq ft |
| Pleats | not listed | 124 | not listed |
| Media weight | 3 oz/yd² | 3 oz/yd² | not listed |
Where to buy
Search any retailer for C-6330 or PWK30 or FC-3915. These are the same cartridge under different brand names.
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OEM part numbers this cartridge replaces
As printed in the cited aftermarket catalogs. Match the number on your old cartridge or in your spa manual exactly.
Hot tub brands that use it
From the spa-manufacturer cross reference in the Unicel 2026 Replacement Guide. A brand may use several sizes, so check your measurements.
- Hot Springs Spas (OEM 31489, 71825, 71826) Unicel p.39
FAQ
What is the Unicel equivalent of Pleatco PWK30?
The catalogs cross-reference Pleatco PWK30 to Unicel C-6330.
What is the Filbur equivalent of Pleatco PWK30?
The catalogs list Filbur FC-3915.
What size is the PWK30 filter?
Pleatco lists PWK30 as 5-7/8" outside diameter by 10-1/2" long, top: 1-15/16" open, bottom: 1-15/16" open, 30 sq ft.
Which OEM part numbers does it replace?
Listed OEM numbers: 31489, 71825, 71826.
Sources: Filbur Product Catalog and Reference Guide (2024) · Pleatco 2023 Catalog & Cross Reference Guide (Pentair) · Pleatco 2023 Catalog & Cross Reference Guide (Pentair) · Pleatco 2023 Catalog & Cross Reference Guide (Pentair) · Unicel 2026 Replacement Guide. Last checked 2026-10-21.