Pleatco PAT25P4 = Unicel 6CH-26 = Filbur FC-0310

25 sq ft hot tub filter, 5-15/16" diameter × 7-1/8" long. Top: Handle · Bottom: 1-1/2" MPT. Pleatco application: Atlantic Pools, Skim Filter 25 SF.

Interchangeable cartridges

Unicel 6CH-26 confirmed by: Pleatco p.47 (Unicel to Pleatco cross reference) Unicel p.12 (Cartridges by series (dimensional listing))
Filbur FC-0310 confirmed by: Filbur p.34 (Reverse cross reference (Unicel to Filbur))

Published dimensions, side by side

Each manufacturer measures a little differently. Compare these with your old cartridge.

As published by	Pleatco PAT25P4 source	Unicel 6CH-26 source
Outside diameter	5-15/16"	6"
Length	7-1/8"	7"
Top end	Handle	/ semi-circular handle
Bottom end	1-1/2" MPT	/ 1-1/2" male thread/MPT
Filter area	25 sq ft	25 sq ft
Pleats	not listed	158
Media weight	3 oz/yd²	3 oz/yd²

Where to buy

Search any retailer for 6CH-26 or PAT25P4 or FC-0310. These are the same cartridge under different brand names.

In The Swim (link coming soon)FiltersFast (link coming soon)Check price at Amazon

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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.

FAQ

What is the Unicel equivalent of Pleatco PAT25P4?

The catalogs cross-reference Pleatco PAT25P4 to Unicel 6CH-26.

What is the Filbur equivalent of Pleatco PAT25P4?

The catalogs list Filbur FC-0310.

What size is the PAT25P4 filter?

Pleatco lists PAT25P4 as 5-15/16" outside diameter by 7-1/8" long, top: Handle, bottom: 1-1/2" MPT, 25 sq ft.

Sources: Filbur Product Catalog and Reference Guide (2024) · Pleatco 2023 Catalog & Cross Reference Guide (Pentair) · Pleatco 2023 Catalog & Cross Reference Guide (Pentair) · Unicel 2026 Replacement Guide. Last checked 2026-10-21.