Waterway Plastics OEM 817-0018 spa filter (C-6375)

Dyna-Flo XL

Replacement numbers

Unicel C-6375, Filbur FC-3754

Fits Waterway Plastics OEM 817-0018.

Diameter 6-9/16" (167 mm)Length 13-5/16" (338 mm)75 sq ft

Disclosure: we may earn a commission from qualifying purchases made through retailer links on this site, at no extra cost to you. As an Amazon Associate I earn from qualifying purchases. Search on Amazon opens an Amazon search for this part number, not one listing we pre-checked. These are affiliate links. Product photos are omitted unless Amazon supplied one through the Product Advertising API or a SiteStripe image link. Verify dimensions before ordering. Each “Check price on Amazon” button opens a specific listing whose title we checked. The line under the name repeats only that title. See our affiliate disclosure.

UnicelC-6375
Pleatconot found in source (No C-6375 line in the 2023 Unicel cross-reference.)
FilburFC-3754
Top2-3/8" (60 mm) open
Bottom2-3/8" (60 mm) open
Ø 6-9/16" (167 mm)13-5/16" (338 mm)Side view · end views belowTopBottom
Top: 2-3/8" (60 mm) open
Bottom: 2-3/8" (60 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. 75 sq ft media.

Request a filter replacement reminder

This stores a request for this filter: the model, the date you installed it, and how often you replace it. Submitting stores the request and does not send email.

We'll only use your email for this request.

Deletion requests go only to the address on the privacy page.

Waterway Plastics files this cartridge as C-6375 cartridge (OEM 817-0018), in the Dyna-Flo XL group. Numbers on the row: OEM 817-0018; Unicel C-6375; Filbur FC-3754. 6-9/16" across, 13-5/16" long, top 2-3/8" open, bottom 2-3/8" open, 75 sq ft.

What the sources add about 817-0018: Dyna-Flo XL, 75 sq ft. Waterway's table writes 2-3/8" x 6-9/16" x 13-5/16", which is the open end, the outside diameter, and the length. Unicel's spec table prints the same three numbers, 224 pleats, 75 sq ft. Filbur FC-3754 agrees and names 817-0018. The 2023 Pleatco cross-reference has no C-6375 line. The longer Dyna-Flo, 817-0019 / C-6310, is a different cartridge and is not this row.

C-6375 (OEM 817-0018), Pleatco side: No C-6375 line in the 2023 Unicel cross-reference..

817-0018, Filbur note: Waterway section PDF p.28: FC-3754, 6-9/16" x 13-5/16", open 2-3/8", OEM 817-0018, C-6375, 75 sq ft..

Before ordering C-6375, compare it with C-4326 differs by Unicel C-4326, Pleatco PRB25-IN, Filbur FC-2375, 4-15/16" diameter, top 2-1/8" open, bottom 2-1/8" open, 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.; and C-4950 differs by Unicel C-4950, Pleatco PRB50-IN, Filbur FC-2390, 4-15/16" diameter, top 2-1/8" open, bottom 2-1/8" open, 50 sq ft, OEM 817-5000, note says 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..

Pleatco does not have a number on this row. Search 817-0018 or the Waterway Plastics part you pulled out of the spa.

Left blank on purpose: No Pleatco equivalent in the 2023 cross-reference..

Source locations for this Waterway Plastics row: Unicel 2026 Replacement Guide on C-6375 (Waterway list PDF p.64: 817-0018 = C-6375, Dyna-Flo XL, 6-9/16" x 13-5/16", 75 sq ft. Spec table PDF p.13: open 2-3/8", 224 pleats.). Waterway Plastics Service Logic cartridge table on C-6375 (Fetched 2026-11-09: 817-0018, 75 sq ft Dyna-Flo XL, 2-3/8" x 6-9/16" x 13-5/16"). Filbur Catalog & Reference Guide on C-6375 (Waterway section PDF p.28: FC-3754, OEM 817-0018, C-6375, 75 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.

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.

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

Sources

Not in sources: No Pleatco equivalent in the 2023 cross-reference..