Listing we opened and checked. Match the diameter, length and both fittings on this page before you order. The price is on Amazon; we do not print one.
Waterway Plastics OEM 817-0050 spa filter (6CH-940)
Front access skim filter
Replacement numbers
Unicel 6CH-940, Pleatco PWW50P3
Fits Waterway Plastics OEM 817-0050.
Diameter 6" (152 mm)Length 8-1/4" (210 mm)45 sq ftUnicel 6CH-940
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| Unicel | 6CH-940 |
|---|---|
| Pleatco | PWW50P3 (Spec table PDF p.33: PWW50P3, 6" x 7-5/8", 1-1/2" SAE, 50 sq ft, OEM 817-0050, 03FIL1400, 25252, 378902, and PWW50, '2 required.' Cross-reference PDF p.47: 6CH-940 = PWW50P3.) |
| Filbur | FC-0359 |
| Top | semi-circular handle |
| Bottom | 1-1/2" SAE |
Bottom: 1-1/2" SAE
Drawn to scale from the listed diameter and length. Handles, threads and closed ends are drawn as symbols, not to scale. 45 sq ft media.
For Waterway Plastics, 6CH-940 cartridge (OEM 817-0050) sits in Front access skim filter. The cross-reference prints OEM 817-0050; Unicel 6CH-940; Pleatco PWW50P3; Filbur FC-0359. 6" across, 8-1/4" long, top semi-circular handle, bottom 1-1/2" SAE, 45 sq ft.
817-0050 carries this note from the catalogs: 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.
6CH-940 (OEM 817-0050), Pleatco side: Spec table PDF p.33: PWW50P3, 6" x 7-5/8", 1-1/2" SAE, 50 sq ft, OEM 817-0050, 03FIL1400, 25252, 378902, and PWW50, '2 required.' Cross-reference PDF p.47: 6CH-940 = PWW50P3..
817-0050, Filbur note: Waterway section PDF p.28: FC-0359, 6 x 8-1/4, 1-1/2" SAE, OEM 817-0050, PWW50P3, 6CH-940, sq ft column 40, two cartridges side by side..
6CH-940 is easy to confuse on the Waterway Plastics table. 6CH-941 differs by Unicel 6CH-941, no Pleatco number, Filbur FC-0360, bottom 1-3/4" male slip, OEM 817-0011, note says Upper half of the stacked front-access pair. Unicel says 6CH-941 must be used with 6CH-942. Waterway's table calls 817-0011 a 50 sq ft upper cartridge. The spec table prints 45 sq ft and 225 pleats, which is the figure stored here. The bottom is a 1-3/4" male slip, not the 1-1/2" SAE of 817-0050. Pleatco's live number is the pair, PWW100P3-SET, 6" x 16-1/2" and 100 sq ft, so it is not stored as the equivalent of this one cartridge. Filbur's description says 40 sq ft and the Waterway sq ft column prints 80.. 6CH-942 differs by Unicel 6CH-942, no Pleatco number, Filbur FC-0361, top 1-3/4" open, OEM 817-0012, note says Lower half of the stacked front-access pair. Top is 1-3/4" open so the upper cartridge's slip can enter it. Bottom is 1-1/2" SAE. Unicel says it must be used with 6CH-941. Waterway's table calls 817-0012 a 50 sq ft lower cartridge. The spec table prints 45 sq ft, stored here. Filbur's description says 40 and the Waterway column prints 80. Pleatco's PWW100P3-SET is the pair, not this cartridge alone..
Left blank on purpose: Area 50 (Waterway table and Unicel Waterway line) vs 45 (Unicel spec table and Unicel product list) vs 40 (Filbur sq ft column). Length 8-1/4" vs Pleatco 7-5/8"..
Source locations for this Waterway Plastics row: Unicel 2026 Replacement Guide on 6CH-940 (Waterway list PDF p.64: 817-0050 = 6CH-940, 6" x 8-1/4", 50 sq ft, and a second line at 100 sq ft with two cartridges side by side. Spec table PDF p.12: 45 sq ft, 225 pleats, 1-1/2" SAE. Product list PDF p.61: 45 sq ft.). Waterway Plastics Service Logic cartridge table on 6CH-940 (Fetched 2026-11-09: 817-0050, 50SF, 6" x 8-1/4", F/A skimmer). Pleatco 2023 Catalog on 6CH-940 (Spec table PDF p.33: PWW50P3, 6" x 7-5/8", 50 sq ft, OEM 817-0050. Cross-reference PDF p.47: 6CH-940 = PWW50P3.). Filbur Catalog & Reference Guide on 6CH-940 (Waterway Plastics section PDF p.28: FC-0359, OEM 817-0050, 6CH-940, sq ft column 40).
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 6CH-940 number is also on the Master Spas page.
Other Waterway Plastics cartridges
- 6CH-941 cartridge (OEM 817-0011), 6" (152 mm) × 8-1/4" (210 mm)
- 6CH-942 cartridge (OEM 817-0012), 6" (152 mm) × 8-1/4" (210 mm)
- 4CH-935 cartridge (OEM 817-4035), 4-15/16" (125 mm) × 9-1/4" (235 mm)
- C-6375 cartridge (OEM 817-0018), 6-9/16" (167 mm) × 13-5/16" (338 mm)
- C-4326 cartridge (OEM 817-2500), 4-15/16" (125 mm) × 13-5/16" (338 mm)
- C-4950 cartridge (OEM 817-5000), 4-15/16" (125 mm) × 13-5/16" (338 mm)
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.
Cleaner and test strips
Hose rinse and soak steps are in how to clean a cartridge. Named cleaners and strips are in filter cleaners and test strips.
Filter cleaner and test strips
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Leisure Time O Filter Clean Cartridge Cleaner Listing title: cartridge cleaner, 32 fl oz.
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SpaGuard Filter Cleaner Listing title: filter cleaner for spas and hot tubs, 1 quart.
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AquaChek SPA 6-in-1 Test Strips Listing title: reads total bromine, total chlorine, free chlorine, pH, total alkalinity and total hardness.
Unicel 6CH-940 Listing we opened and checked. Match the diameter, length and both fittings on this page before you order. The price is on Amazon; we do not print one.
Sources
- Unicel 2026 Replacement Guide: Waterway list PDF p.64: 817-0050 = 6CH-940, 6" x 8-1/4", 50 sq ft, and a second line at 100 sq ft with two cartridges side by side. Spec table PDF p.12: 45 sq ft, 225 pleats, 1-1/2" SAE. Product list PDF p.61: 45 sq ft. (PDF)
- Waterway Plastics Service Logic cartridge table: Fetched 2026-11-09: 817-0050, 50SF, 6" x 8-1/4", F/A skimmer (web page)
- Pleatco 2023 Catalog: Spec table PDF p.33: PWW50P3, 6" x 7-5/8", 50 sq ft, OEM 817-0050. Cross-reference PDF p.47: 6CH-940 = PWW50P3. (PDF)
- Filbur Catalog & Reference Guide: Waterway Plastics section PDF p.28: FC-0359, OEM 817-0050, 6CH-940, sq ft column 40 (PDF)
Not in sources: Area 50 (Waterway table and Unicel Waterway line) vs 45 (Unicel spec table and Unicel product list) vs 40 (Filbur sq ft column). Length 8-1/4" vs Pleatco 7-5/8"..