Pleatco PRB8.5 = Unicel C-2303 = Filbur FC-2324
9 sq ft hot tub filter, 2-7/8" diameter × 17-1/16" long. Top: 2-1/8" open · Bottom: 2-1/8" open. Pleatco application: Rainbow Chloro.
Interchangeable cartridges
- Unicel C-2303 confirmed by: Pleatco p.47 (Unicel to Pleatco cross reference) Unicel p.5 (Cartridges by series (dimensional listing))
- Filbur FC-2324 confirmed by: Pleatco p.48 (Filbur to Pleatco cross reference) Filbur p.33 (Reverse cross reference (Unicel to Filbur)) Filbur p.8 (Dimensional cartridge listing)
Check before you order
- Unicel C-2303 rates it 8.5 sq ft (vs 9 sq ft); filter area ratings differ by maker.
Published dimensions, side by side
Each manufacturer measures a little differently. Compare these with your old cartridge.
| As published by | Pleatco PRB8.5 source | Unicel C-2303 source | Filbur FC-2324 source |
|---|---|---|---|
| Outside diameter | 2-7/8" | 2-7/8" | 2-7/8" |
| Length | 17-1/16" | 17-1/16" | 17-1/16" |
| 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 | 9 sq ft | 8.5 sq ft | 9 sq ft |
| Pleats | not listed | 150 | not listed |
| Media weight | 3 oz/yd² | 3 oz/yd² | not listed |
Where to buy
Search any retailer for C-2303 or PRB8.5 or FC-2324. 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 |
|---|---|
17-0052 | Pleatco p.31: 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.
- Emerald Spas Unicel p.34
- Pentair Pool Prod - Rainbow Plastics (models: Chloro cartridge; OEM 17-0052) Unicel p.52
FAQ
What is the Unicel equivalent of Pleatco PRB8.5?
The catalogs cross-reference Pleatco PRB8.5 to Unicel C-2303.
What is the Filbur equivalent of Pleatco PRB8.5?
The catalogs list Filbur FC-2324.
What size is the PRB8.5 filter?
Pleatco lists PRB8.5 as 2-7/8" outside diameter by 17-1/16" long, top: 2-1/8" open, bottom: 2-1/8" open, 9 sq ft.
Which OEM part numbers does it replace?
Listed OEM numbers: 17-0052.
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.