Which filter does my Freedom spa take?

Reviewed November 6, 2026

Unicel’s Freedom Spas list names Franklin, Statesman and Revere for a 4-5/8" × 11-7/8" cartridge with a 1-1/2" MPT bottom, 4CH-30, at 30 sq ft. The same list names Statesman, Lexington, Enterprise, Aristocrat and Franklin for a 6" × 12-3/8" cartridge, 6CH-45, at 45 sq ft. Franklin and Statesman are on both rows, so the model name does not finish the order. Filbur prints 6CH-45 at 12-1/4" long, not 12-3/8". Liberty is named only on the short open cartridge, 35 sq ft C-4401. The next row, 50 sq ft C-4405, has no model name and the note “Model dated after 1993.” Concord, Patriot, Ambassador and Executive are named only on the 37 sq ft C-4637. The 50 sq ft C-4950 row under them also has no model name and the same 1993 note.

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The cartridges, with equivalents

Factory part	What it is	Catalog equivalents	Rated area	Our page
No Freedom part number in Unicel	Franklin, Statesman, Revere. Aladdin 13005 uses that same model string and lists Freedom among many brands.	Unicel 4CH-30; Filbur FC-0141; Pleatco number in Filbur’s cell: PTL25P-4. Not in Pleatco’s Unicel cross-reference.	4-5/8" × 11-7/8", cone handle, 1-1/2" MPT. 30 sq ft on the Freedom line, the spec table, Filbur’s size table and Aladdin. 25 sq ft on Unicel’s Sundance line for OEM 6540-484.	4CH-30
No Freedom part number in Unicel	Statesman, Lexington, Enterprise, Aristocrat, Franklin. Aladdin 14506 uses that model string for Freedom Spas and Master Spas.	Unicel 6CH-45; Filbur FC-0330; Pleatco number in Filbur’s cell: PTL45W-P-4	Unicel and Aladdin: 6" × 12-3/8", 158 pleats, 45 sq ft, 1-1/2" MPT. Filbur: 6" × 12-1/4".	6CH-45
No Freedom part number in Unicel	Liberty, on the 35 sq ft row only. Filbur does not print Liberty. It calls this row Rainbow DSF 35, two per set.	Unicel C-4401; Pleatco PRB17.5SF-PAIR; Filbur FC-2386	4-15/16" × 4-5/8", open 2-1/8", 35 sq ft, two per set in the spec note and in Filbur	C-4401
No model name on this row	50 sq ft open cartridge. Note under the row: “Model dated after 1993.” Filbur repeats that note and calls the row Rainbow DSF 50, two per set.	Unicel C-4405; Pleatco PRB25SF-PAIR; Filbur FC-2387	4-15/16" × 6-5/8", open 2-1/8", 50 sq ft	C-4405
No Freedom part number in Unicel	Concord, Patriot, Ambassador, Executive, on this 37 sq ft row only. Filbur calls it Rainbow Dynamic 37 and does not print those model names. The spec table’s application line names Rainbow, Waterway, Morgan, Leisure Bay and Custom Molded Products, not Freedom.	Unicel C-4637; Filbur FC-2380; Pleatco number in Filbur’s cell: PRB37-IN-4	4-15/16" × 13-5/16", open 2-1/8" both ends, 158 pleats, 4 oz, 37 sq ft	C-4637
No model name on this row	50 sq ft open cartridge. Note under the row: “Model dated after 1993.” Filbur repeats that note as Rainbow Dynamic 50.	Unicel C-4950; Pleatco PRB50-IN; Filbur FC-2390	4-15/16" × 13-5/16", open 2-1/8", 50 sq ft	C-4950

Model names in the first column are Unicel’s, except where the cell says otherwise. Filbur’s Freedom Spas section lists the same Unicel numbers and does not print Franklin, Liberty or Concord. It describes several of those rows as Rainbow cartridges, and it also files Freeflow’s CLX, TLX, RLX and Legend in this section. Those Freeflow names are on the Freeflow lookup, not in the table below. Aladdin is a second catalog for the two threaded cartridges only.

Two threaded cartridges, and two models on both

Unicel prints no Freedom factory number. The model names are the left-hand column of the Freedom Spas block. Franklin, Statesman and Revere share the line with 4CH-30. Statesman, Lexington, Enterprise, Aristocrat and Franklin share the next line with 6CH-45. Franklin and Statesman are in both groups. A Statesman owner still has to measure.

	4CH-30	6CH-45
Unicel Freedom list and spec table	4-5/8" × 11-7/8", molded cone handle, 1-1/2" MPT, 158 pleats, 4 oz, 30 sq ft	6" × 12-3/8", semi-circular handle, 1-1/2" MPT, 158 pleats, 3 oz, 45 sq ft
Unicel Sundance line, same 4CH-30 number	OEM 6540-484, 25 sq ft, not 30. Same diameter, length and thread.	Not on that line
Filbur size table	FC-0141, 4-5/8" × 11-7/8", 30 sq ft, PTL25P-4	FC-0330, 6" × 12-1/4", 45 sq ft, PTL45W-P-4
Filbur Freedom section	FC-0141, 30 sq ft. No Franklin / Statesman / Revere names.	FC-0330, 6" × 12-1/4", 45 sq ft. No Lexington names.
Aladdin	Part 13005. Model field: “4CH-Top Load, Franklin, Statesman, Revere.” 30 sq ft, 158 pleats, 4-5/8" × 11-7/8", cone handle, 1-1/2" male thread. Freedom is one brand in a long manufacturer list that also includes Dimension One and Sundance.	Part 14506. Model field: “6CH-Top Load/Statesman/Lexington/Enterprise/Aristocrat/Franklin.” 45 sq ft, 158 pleats, 6" × 12-3/8". Manufacturers named: Freedom Spas, Master Spas, and the filter brands.

The 30-versus-25 sq ft split on 4CH-30 is already how the Sundance 6540-484 row is filed: that OEM line says 25, and the spec table says 30. Freedom’s own line matches the spec table. Order for a Freedom spa from the 30 sq ft description, then hold the new cartridge against the old one. The length fight on 6CH-45 is 12-3/8" (Unicel spec, Unicel’s Freedom line, Aladdin) against 12-1/4" (Filbur’s size table and Filbur’s Freedom section). An eighth of an inch is inside some catalogs’ measuring tolerance and outside others. Measure the cartridge you removed. The Master Spas 6CH-45 row uses Unicel’s 12-3/8" and has no Freedom model names.

Liberty, the 1993 note, and the open cartridges

Under the threaded pair, Unicel prints Liberty on one row only: 35 sq ft, 4-15/16" × 4-5/8", C-4401, 4 oz. The following row is 50 sq ft, 4-15/16" × 6-5/8", C-4405, with a blank model cell, and the note “Model dated after 1993” sits under that row. The note does not say “Liberty.” It does not say the 35 sq ft cartridge was dropped. Filbur’s Freedom section lists FC-2386 / C-4401 as “Rainbow DSF 35, 2/set” and FC-2387 / C-4405 as “Rainbow DSF 50, 2/set,” and it puts “Model dated after 1993” on the 50 sq ft row. Filbur does not print the word Liberty. Unicel’s spec note on C-4401 says two cartridges per set with a stick handle, which matches Filbur’s “2/set” and the Beachcomber pre-1995 set that uses the same Unicel number for a different brand.

Concord, Patriot, Ambassador and Executive are printed on the 37 sq ft row: 4-15/16" × 13-5/16", C-4637, 4 oz. The spec table gives that cartridge 158 pleats, 2-1/8" open ends, and calls it an upgrade of the 25 sq ft C-4326 and C-4625. The brands on that spec line are Rainbow, Waterway Plastics, Morgan Spas, Leisure Bay Spas and Custom Molded Products. Freedom is not among them. The Freedom model names for C-4637 come from the OEM cross-reference only. Filbur’s Freedom section lists FC-2380 / C-4637 as “Rainbow Dynamic 37” and does not print Concord, Patriot, Ambassador or Executive.

The last Freedom row is 50 sq ft, 4-15/16" × 13-5/16", C-4950, blank model cell, and another “Model dated after 1993” note under it. Filbur repeats the note on FC-2390 and calls the row Rainbow Dynamic 50. C-4950 is a cartridge several other brands use. Unicel does not say it replaced C-4637. The note is the only date either catalog gives, and it is attached to the 50 sq ft row, not to the Concord names.

Same outside length, two areas: C-4637 at 37 sq ft and C-4950 at 50 sq ft are both 13-5/16" long. That is the pleat-count difference in why same-size filters have different square-foot ratings. Both are open at 2-1/8", so a thread is the wrong clue. Open-end versus threaded shows the difference.

Where the sources disagree

Franklin and Statesman. Unicel names both on 4CH-30 and on 6CH-45. Aladdin’s two model fields do the same. The cartridges are 4-5/8" × 11-7/8" and 6" × 12-3/8".
4CH-30 area. Freedom list, spec table, Filbur’s size table and Aladdin: 30 sq ft. Unicel’s Sundance line for OEM 6540-484: 25 sq ft. Filbur’s Sundance line for that OEM also prints 25.
6CH-45 length. Unicel and Aladdin 12-3/8". Filbur 12-1/4".
Liberty. Unicel only, and only on the 35 sq ft row. Filbur’s matching row says Rainbow DSF 35, two per set.
“Model dated after 1993.” Printed under the blank-model C-4405 row and under the blank-model C-4950 row, in Unicel and again in Filbur. Not printed on the Liberty row or the Concord row.
Concord and the other three names. Unicel’s Freedom list only. Filbur says Rainbow Dynamic 37. The spec table does not name Freedom.
Freeflow names inside Filbur’s Freedom section. CLX, TLX, RLX and Legend are in that section. Unicel files them under Freeflow, on the next heading. They are not Freedom model names in Unicel.

How to confirm yours

A threaded cartridge about 4-5/8" × 11-7/8" is 4CH-30 / FC-0141. One about 6" across and about 12" long is 6CH-45 / FC-0330. Franklin or Statesman on a brochure does not choose between them.
An open cartridge about 4-5/8" long, two to a set, is the C-4401 / Liberty description. About 6-5/8" long, still open and two to a set, is the C-4405 row with the 1993 note and no model name.
An open cartridge about 13-5/16" long is either 37 sq ft (C-4637) or 50 sq ft (C-4950). The 1993 note is on the 50, not on the Concord names.
Use the Freedom Spas table for the sizes, and the Freeflow lookup if the model is TLX, RLX, CLX, Legend or Passport.

Why one cartridge size can carry two different square-foot ratings: our explainer with Unicel’s pleat-count table.

Sources

This page summarizes published catalogs and dealer fitment tables; always follow your own spa’s owner’s manual. See our disclaimer and methodology.