Waterway Plastics OEM 817-0010 spa filter (C-4310)

Skim filter 10

Replacement numbers

Unicel C-4310, Pleatco PWW10

Fits Waterway Plastics OEM 817-0010.

Diameter 4-1/4" (108 mm)Length 4" (102 mm)10 sq ft

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UnicelC-4310
PleatcoPWW10 (Spec table: PWW10, 4-1/4" x 4", 2-1/16" open, 10 sq ft, OEM 817-0010. PWW10PAIR is 20 sq ft. Cross-reference PDF p.47: C-4310 = PWW10.)
FilburFC-3077
Top2-1/16" (52 mm) open
Bottom2-1/16" (52 mm) open
Ø 4-1/4" (108 mm)4" (102 mm)Side view · end views belowTopBottom
Top: 2-1/16" (52 mm) open
Bottom: 2-1/16" (52 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. 10 sq ft media.

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Skim filter 10 is the group name on the Waterway Plastics row C-4310 cartridge (OEM 817-0010). Match these numbers: OEM 817-0010; Unicel C-4310; Pleatco PWW10; Filbur FC-3077. 4-1/4" across, 4" long, top 2-1/16" open, bottom 2-1/16" open, 10 sq ft.

What the sources add about 817-0010: 10 sq ft skim filter, open both ends. Unicel, Pleatco, and Waterway's table agree on 10 sq ft and on 4-1/4" x 4". Unicel and Pleatco print 2-1/16" openings and 216 pleats in Unicel's spec table. Filbur FC-3077 prints the top opening as 1-15/16". Pleatco also lists PWW10PAIR at 20 sq ft for two of this cartridge. That pair is not a different body.

C-4310 (OEM 817-0010), Pleatco side: Spec table: PWW10, 4-1/4" x 4", 2-1/16" open, 10 sq ft, OEM 817-0010. PWW10PAIR is 20 sq ft. Cross-reference PDF p.47: C-4310 = PWW10..

817-0010, Filbur note: Waterway section PDF p.28: FC-3077, 4-1/4" x 4", top opening 1-15/16", OEM 817-0010, PWW10, C-4310, 10 sq ft..

Before ordering C-4310, compare it with 4CH-935 differs by Unicel 4CH-935, Pleatco PWW35L, Filbur FC-0170, 4-15/16" diameter, 9-1/4" long, top v-groove handle, bottom 2" female SAE, 35 sq ft, OEM 817-4035, note says Short Teleweir. Unicel and Waterway's table: 4-15/16" x 9-1/4", 35 sq ft, 2" female SAE, 219 pleats, for a 1-1/2" male SAE standpipe. Pleatco PWW35L is 5" x 8-1/2", 35 sq ft, OEM 817-4035, 1-1/2" female SAE. Filbur's Waterway row FC-0170 prints 817-4035 at 4-15/16" x 9-1/4" and 30 sq ft, with Unicel N/A. Nordic's chart uses this Waterway number as CARTRIDGE-T35. The 35 stored here is Unicel's and Waterway's figure.; and 6CH-940 differs by Unicel 6CH-940, Pleatco PWW50P3, Filbur FC-0359, 6" diameter, 8-1/4" long, top semi-circular handle, bottom 1-1/2" SAE, 45 sq ft, OEM 817-0050, note says Front-access cartridge. Waterway's Service Logic table (fetched 2026-11-09) calls 817-0050 a 50 sq ft, 6" x 8-1/4" F/A skimmer cartridge. Unicel's Waterway list prints the same 50 sq ft, and a second line at 100 sq ft with the note that two cartridges are used side by side. The spec table and Unicel's own product list print 6CH-940 at 45 sq ft, 225 pleats. The 45 stored here is the spec-table figure. Pleatco PWW50P3 is 6" x 7-5/8", 50 sq ft, and says two are required. Filbur FC-0359's sq ft column is 40..

Left blank on purpose: Top opening 2-1/16" (Unicel, Pleatco) vs 1-15/16" (Filbur)..

Pages checked for 817-0010: Unicel 2026 Replacement Guide on C-4310 (Waterway list PDF p.64: 817-0010 = C-4310, 4-1/4" x 4", 10 sq ft. Spec table PDF p.6: open 2-1/16", 216 pleats.). Waterway Plastics Service Logic cartridge table on C-4310 (Fetched 2026-11-09: 817-0010, 10 sq ft skim filter). Pleatco 2023 Catalog on C-4310 (PWW10 spec: 4-1/4" x 4", 2-1/16" open, 10 sq ft, OEM 817-0010. Cross-reference PDF p.47: C-4310 = PWW10.). Filbur Catalog & Reference Guide on C-4310 (Waterway section PDF p.28: FC-3077, OEM 817-0010, C-4310, 10 sq ft, top opening 1-15/16").

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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.

The same C-4310 number is also on the PDC Spas page.

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Sources

Not in sources: Top opening 2-1/16" (Unicel, Pleatco) vs 1-15/16" (Filbur)..