Dimension One Spas OEM 1561-03 spa filter (C-4340)

Dimension One Spas

Replacement numbers

Unicel C-4340, Pleatco PMT40

Fits Dimension One Spas OEM 1561-03.

Diameter 4-15/16" (125 mm)Length 11-5/8" (295 mm)40 sq ft1 model listed

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UnicelC-4340
PleatcoPMT40 (as printed in the Filbur catalog Dimension One Spas section (printed p.33); not found in the Pleatco 2023 Unicel cross reference)
FilburFC-3081
Top2-1/8" (54 mm) / open
Bottom2-1/8" (54 mm) / open
Ø 4-15/16" (125 mm)11-5/8" (295 mm)Side view · end views belowTopBottom
Top: 2-1/8" (54 mm) / open
Bottom: 2-1/8" (54 mm) / open
Drawn to scale from the listed diameter and length and open-end sizes. Handles, threads and closed ends are drawn as symbols, not to scale. 40 sq ft media.

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For Dimension One Spas, C-4340 cartridge (OEM 1561-03) sits in Dimension One Spas. The cross-reference prints OEM 1561-03; Unicel C-4340; Pleatco PMT40; Filbur FC-3081. 4-15/16" across, 11-5/8" long, top 2-1/8" / open, bottom 2-1/8" / open, 40 sq ft.

Catalog note for 1561-03: Discontinued by Dimension One Spas (noted in both the Unicel guide and the Filbur catalog); the replacement cartridge is still made.

PMT40 is the Pleatco string Filbur prints next to C-4340 (OEM 1561-03) on printed p.33. PMT40 itself is absent from Pleatco’s 2023 Unicel cross-reference.

Model list attached to C-4340 cartridge (OEM 1561-03): Dimension One Arena, Diamante, Quadra, years 1994, listed by Hot Tub Outpost OEM listing.

C-4340 is easy to confuse on the Dimension One Spas table. 4CH-30 differs by Unicel 4CH-30, Pleatco PTL25P-4, Filbur FC-0141, 4-5/8" diameter, 11-7/8" long, top molded cone handle, bottom 1-1/2” male thread/MPT, 25 sq ft, OEM 1561-14, note says Unicel's spec table rates 4CH-30 at 30 sq ft (4 oz media); its OEM cross reference and Filbur both give 25 sq ft for the Dimension One part, which is the figure shown.. 4CH-950 differs by Unicel 4CH-950, Pleatco PDO-UF25P2, Filbur FC-0173, 4-5/8" diameter, 12" long, top semi-circular handle, bottom 1-1/4" SAE thread, 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..

Source locations for this Dimension One Spas row: Unicel 2026 Replacement Guide on C-4340 (OEM cross reference (Dimension One Spas section), PDF p.33 (printed p.29); spec table PDF p.8 (printed p.4)). Filbur Catalog & Reference Guide on C-4340 (Product by Pool/Spa Manufacturer (OEM), Dimension One Spas, printed p.33 (PDF p.17)). Hot Tub Outpost (retailer OEM listing) on C-4340 (01561-03: 4-7/8" x 11-5/8", 2-1/8" open top and bottom, 40 sq ft; 1994 Arena, Diamante and Quadra).

Hot tubs listed for this cartridge

The rest of the Dimension One Spas model list is the Dimension One Spas filter by model and year lookup.

Model / systemYearsListed by
Dimension One Arena, Diamante, Quadra1994Hot Tub Outpost OEM listing

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.

Other Dimension One Spas cartridges

All 12 Dimension One Spas spa filters

Every number on this row, on one screen: cross-reference lookup. Published clean and replace intervals for this cartridge, and a buy link for the numbers above: replacement schedule and reorder. The interval comparison by brand: calculator.

Cleaner and test strips

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Filter cleaner and test strips

Sources