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Replacement Filter Cartridges

Waterway TWM & In-Line Filter Cartridges

Replacement cartridges for Waterway® TWM and top-load in-line spa filter housings (35 and 50 sq ft open/open elements). These share elements with the Rainbow Dynamic in-line series — match the Unicel number in the chart below the products.

2 of 2 cartridges

Excel Filters makes replacement cartridges for Waterway® TWM and in-line spa filter housings — the 35 sq ft and 50 sq ft open/open elements. These share elements with the Pentair/Rainbow Dynamic in-line series, so match the Unicel C-4-series number on your current cartridge.

Waterway TWM & In-Line Filter Cartridges compatibility

These are open/open in-line cartridges. They share elements with the Pentair/Rainbow Dynamic in-line series — match the Unicel number on your cartridge.

Housing modelUnicelPleatcoFilburExcel replacementQty per housing
TWM / in-line 35 sq ft (open/open)C-4335PRB35-INFC-2385XLS-4181
TWM / in-line 50 sq ft (open/open)C-4950PRB50-INFC-2390XLS-4081

Frequently asked questions

How do I identify my Waterway in-line cartridge?

Read the Unicel number on the end cap — C-4335 is the 35 sq ft element (XLS-418) and C-4950 is the 50 sq ft element (XLS-408). Both are open/open (a hole at each end); confirm your current cartridge has the same geometry before ordering.

Are these the same as the Rainbow Dynamic in-line cartridges?

Yes — the Waterway TWM / in-line 35 and 50 sq ft elements are the same cartridges used in the Pentair/Rainbow Dynamic in-line series. Either housing leads to the same Excel replacement.

Are these genuine Waterway parts?

No. Excel Filters cartridges are aftermarket replacements manufactured in the USA to OEM dimensions and media area. They are not affiliated with or endorsed by Waterway.