Waterway Plastics OEM 817-5000 spa filter (C-4950)

Top load 50

Replacement numbers

Unicel C-4950, Pleatco PRB50-IN

Fits Waterway Plastics OEM 817-5000.

Diameter 4-15/16" (125 mm)Length 13-5/16" (338 mm)50 sq ft

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UnicelC-4950
PleatcoPRB50-IN (Spec table PDF p.32: PRB50-IN, 5" x 13-5/16", open 2-1/8", 50 sq ft, OEM list includes 817-5000.)
FilburFC-2390
Top2-1/8" (54 mm) open
Bottom2-1/8" (54 mm) open
Ø 4-15/16" (125 mm)13-5/16" (338 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. 50 sq ft media.

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For Waterway Plastics, C-4950 cartridge (OEM 817-5000) sits in Top load 50. The cross-reference prints OEM 817-5000; Unicel C-4950; Pleatco PRB50-IN; Filbur FC-2390. 4-15/16" across, 13-5/16" long, top 2-1/8" open, bottom 2-1/8" open, 50 sq ft.

Catalog note for 817-5000: 50 sq ft open top-load. Same outside size as 817-2500. Unicel's spec note calls C-4950 an upgrade of the 25 sq ft C-4326: 212 pleats against 106, same 4-15/16" x 13-5/16" body. Pleatco PRB50-IN lists OEM 817-5000 at 5" outside diameter. Filbur FC-2390 agrees with Unicel's size and 50 sq ft. Waterway's table calls 817-5000 a 50 sq ft in-line top-load cartridge.

C-4950 (OEM 817-5000), Pleatco side: Spec table PDF p.32: PRB50-IN, 5" x 13-5/16", open 2-1/8", 50 sq ft, OEM list includes 817-5000..

817-5000, Filbur note: Waterway section PDF p.28: FC-2390, 4-15/16" x 13-5/16", open 2-1/8", OEM 817-5000, C-4950, 50 sq ft..

C-4950 is easy to confuse on the Waterway Plastics table. C-4326 differs by Unicel C-4326, Pleatco PRB25-IN, Filbur FC-2375, 25 sq ft, OEM 817-2500, note says 25 sq ft open top-load. Unicel: 4-15/16" x 13-5/16", open 2-1/8", 106 pleats, 25 sq ft. Pleatco PRB25-IN lists OEM 817-2500 at 5" outside diameter and the same length. Filbur prints this OEM on two rows: FC-2375 at 13-5/16" (PRB25-IN, C-4326) and FC-2910, which the size table lengths at 13-1/4" and the Waterway section lengths at 12-1/4", with no Pleatco number. The size stored here is Unicel's. The 50 sq ft cartridge of the same length is 817-5000.. 4CH-926 differs by Unicel 4CH-926, Pleatco PWW25L, Filbur FC-0168, 13-1/2" long, top v-groove handle, bottom 2" female SAE, 25 sq ft, OEM 817-4025, note says Teleweir 25. Unicel and Waterway's table agree: 4-15/16" x 13-1/2", 25 sq ft, SAE thread. Unicel's spec table says 2" female SAE, 105 pleats, for a 1-1/2" male SAE standpipe (the standpipe note is printed on the 4CH-935 and 4CH-949 spec lines). Pleatco PWW25L is 5" x 13-3/16", 1-1/2" female SAE, 25 sq ft, and that spec line does not print 817-4025. The cross-reference does: 4CH-926 = PWW25L. Filbur FC-0168 is 13-1/16" long and 1-1/2" female SAE. Same length as 817-4050, half the area..

Left blank on purpose: Outside diameter 4-15/16" (Unicel, Filbur) vs 5" (Pleatco)..

Where those figures are printed: Unicel 2026 Replacement Guide on C-4950 (Waterway list PDF p.64: 817-5000 = C-4950, 4-15/16" x 13-5/16", 50 sq ft. Spec table PDF p.9: 212 pleats, and the note that C-4950 is an upgrade of C-4326.). Waterway Plastics Service Logic cartridge table on C-4950 (Fetched 2026-11-09: 817-5000, 50 sq ft, in-line top-load). Pleatco 2023 Catalog on C-4950 (Spec table PDF p.32: PRB50-IN includes OEM 817-5000, 5" x 13-5/16", 50 sq ft). Filbur Catalog & Reference Guide on C-4950 (Waterway section PDF p.28: FC-2390, OEM 817-5000, C-4950, 50 sq ft).

If you know the Waterway Plastics model and not the part number, use the Waterway Plastics 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.

The same C-4950 number is also on the Caldera, Jacuzzi, Sundance, Beachcomber, Coleman Spas pages.

Other Waterway Plastics cartridges

All 12 Waterway Plastics 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.

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Filter cleaner and test strips

Sources

Not in sources: Outside diameter 4-15/16" (Unicel, Filbur) vs 5" (Pleatco)..