Dimension One Spas OEM 1561-13 spa filter (4CH-940)

Dimension One Spas (1-1/4" SAE thread)

Replacement numbers

Unicel 4CH-940, Pleatco PDO-UF40P2

Fits Dimension One Spas OEM 1561-13.

Diameter 4-5/8" (117 mm)Length 15" (381 mm)40 sq ft

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Unicel4CH-940
PleatcoPDO-UF40P2 (as printed in the Filbur catalog Dimension One Spas section (printed p.33); not found in the Pleatco 2023 Unicel cross reference)
FilburFC-0177
Topsemi-circular handle
Bottom1-1/4" SAE thread
Ø 4-5/8" (117 mm)15" (381 mm)Side view · end views belowTopBottom
Top: semi-circular handle
Bottom: 1-1/4" SAE thread
Drawn to scale from the listed diameter and length. Handles, threads and closed ends are drawn as symbols, not to scale. 40 sq ft media.

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Dimension One Spas files this cartridge as 4CH-940 cartridge (OEM 1561-13), in the Dimension One Spas (1-1/4" SAE thread) group. Numbers on the row: OEM 1561-13; Unicel 4CH-940; Pleatco PDO-UF40P2; Filbur FC-0177. 4-5/8" across, 15" long, top semi-circular handle, bottom 1-1/4" SAE thread, 40 sq ft.

PDO-UF40P2 is the Pleatco string Filbur prints next to 4CH-940 (OEM 1561-13) on printed p.33. PDO-UF40P2 itself is absent from Pleatco’s 2023 Unicel cross-reference.

4CH-940 is easy to confuse on the Dimension One Spas table. 4CH-50 differs by Unicel 4CH-50, Pleatco PTL50P-4, Filbur FC-0151, 14-3/4" long, top molded cone handle, bottom 1-1/2” male thread/MPT, 50 sq ft, OEM 1561-05. 4CH-950 differs by Unicel 4CH-950, Pleatco PDO-UF25P2, Filbur FC-0173, 12" long, 25 sq ft, OEM 1561-04, note says Unicel gives the length as 12"; Filbur's table prints 11-7/8" (and "4-5/8 x 12" in its description) for FC-0173..

Left blank on purpose: no model/model-year fitment in sources.

Pages checked for 1561-13: Unicel 2026 Replacement Guide on 4CH-940 (OEM cross reference (Dimension One Spas section), PDF p.33 (printed p.29); spec table PDF p.7 (printed p.3)). Filbur Catalog & Reference Guide on 4CH-940 (Product by Pool/Spa Manufacturer (OEM), Dimension One Spas, printed p.33 (PDF p.17)).

If you know the Dimension One Spas model and not the part number, use the Dimension One Spas filter by model and year lookup.

Check the cartridge you removed

Measure diameter, length, and both ends, then compare them with the figures above. The steps are in the measuring guide. Why the bottom decides whether it seals: open-end vs threaded filters. Power, the retainer, and not running the spa empty: how to install a cartridge. Number formats: how Filbur, Unicel and Pleatco numbers compare.

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Cleaner and test strips

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Filter cleaner and test strips

Sources

Not in sources: no model/model-year fitment in sources.