Pleatco PRB25-IN-4 = Unicel C-4625 = Filbur FC-2370
25 sq ft hot tub filter, 5" diameter × 13-5/16" long. Top: 2-1/8" open · Bottom: 2-1/8" open. Pleatco application: Dynamic Series II & III - RTL/RCF, Series I - Model RDC, Series IV - DFM, DFML, Waterway.
Interchangeable cartridges
- Unicel C-4625 confirmed by: Pleatco p.47 (Unicel to Pleatco cross reference) Unicel p.9 (Cartridges by series (dimensional listing))
- Filbur FC-2370 confirmed by: Pleatco p.48 (Filbur to Pleatco cross reference) Filbur p.33 (Reverse cross reference (Unicel to Filbur)) Filbur p.9 (Dimensional cartridge listing)
Published dimensions, side by side
Each manufacturer measures a little differently. Compare these with your old cartridge.
| As published by | Pleatco PRB25-IN-4 source | Unicel C-4625 source | Filbur FC-2370 source |
|---|---|---|---|
| Outside diameter | 5" | 4-15/16" | 4-15/16" |
| Length | 13-5/16" | 13-5/16" | 13-5/16" |
| Top end | 2-1/8" open | 2-1/8" / open | 2-1/8" open |
| Bottom end | 2-1/8" open | 2-1/8" / open | 2-1/8" open |
| Filter area | 25 sq ft | 25 sq ft | 25 sq ft |
| Pleats | not listed | 106 | not listed |
| Media weight | 4 oz/yd² | 4 oz/yd² | not listed |
Where to buy
Search any retailer for C-4625 or PRB25-IN-4 or FC-2370. 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.
| OEM number | Listed in |
|---|---|
17-2325 | Pleatco p.32: OEM part # column Unicel p.52: OEM cross reference: Pentair Pool Prod - Rainbow Plastics |
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.
- Alps Spas Unicel p.26
- Aries Spas Unicel p.28
- Blue Pacific Spas Unicel p.30
- Esther Williams Unicel p.35
- Haughs Unicel p.37
- Heldor Spas Unicel p.39
- Hydro Pool Industries Unicel p.39
- J.E.M. Spas Unicel p.41
- Pentair Pool Prod - Rainbow Plastics (models: Dynamic Series IV - DFM,DFML, Dynamic Series II & III - RTL/RCF, Dynamic Series 1 - Model RDC; OEM 17-2325) Unicel p.52
- Sequoia Design Unicel p.55
- Warm Springs Spa Unicel p.63
FAQ
What is the Unicel equivalent of Pleatco PRB25-IN-4?
The catalogs cross-reference Pleatco PRB25-IN-4 to Unicel C-4625.
What is the Filbur equivalent of Pleatco PRB25-IN-4?
The catalogs list Filbur FC-2370.
What size is the PRB25-IN-4 filter?
Pleatco lists PRB25-IN-4 as 5" outside diameter by 13-5/16" long, top: 2-1/8" open, bottom: 2-1/8" open, 25 sq ft.
Which OEM part numbers does it replace?
Listed OEM numbers: 17-2325.
Sources: Filbur Product Catalog and Reference Guide (2024) · 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.