Which Saratoga spa filter do I have?
The short Saratoga cartridge is one body with two bottoms, and the catalogs do not agree how much area it has. Unicel prints OEM 20241-238 as 4CH-20: 4-5/8" × 6-3/4", 1-1/2" MPT, 20 sq ft. The same length with a 1-1/4" SAE bottom is 4CH-920, also 20 sq ft in Unicel, and that row has no OEM number. Pleatco’s spec for 20241-238 is PSG25P4 at 4-3/4" × 6-1/2" and 25 sq ft. Filbur’s Saratoga section prints both 4CH-20 and 4CH-920 at 15 sq ft. The longer 1-1/2" MPT cartridges are 20245-238 (4CH-21), 20254-238 (4CH-24), and 74407-98 (4CH-30). Filbur’s footnote says the factory cartridge uses an adapter, and the replacement has to match the fitting in the skim well, SAE or MPT.
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The cartridges, with equivalents
| Factory part | What it is | Catalog equivalents | Rated area | Our page |
|---|---|---|---|---|
| 20241-238 | Short top-load, 1-1/2" MPT. This is the number Pleatco sizes differently. Unicel’s Vita line prints the same Unicel cartridge, as PVT 25, at 25 sq ft. | Unicel 4CH-20. Pleatco PSG25P4. Filbur FC-0125. Filbur’s Pleatco cell is PHC25, which Pleatco’s 2023 list deactivates with replacement N/A. | Unicel spec and price index: 4-5/8" × 6-3/4", cone handle, 204 pleats, 20 sq ft. Pleatco: 4-3/4" × 6-1/2", 25 sq ft. Filbur’s Saratoga section: 15 sq ft. Filbur’s size table description says 20 sq ft and its column says 25. | 4CH-20 |
| No OEM on the row | The 1-1/4" SAE twin of 4CH-20. Same length. Do not order 20241-238 for this fitting. | Unicel 4CH-920. Filbur FC-0124. Pleatco’s 2023 Unicel cross-reference has no 4CH-920 line. | Unicel: 4-5/8" × 6-3/4", 204 pleats, 20 sq ft, 1-1/4" SAE. Filbur’s Saratoga section: 15 sq ft, and the Pleatco cell it prints is PSG13.5, which is a shorter cartridge. | 4CH-920 |
| 20245-238 | 1-1/2" MPT, one step longer than 20241-238. Pleatco also prints Vita’s PVT-25N on this number. | Unicel 4CH-21. Pleatco PTL18P4. Filbur FC-0121. | Unicel and Filbur: 4-5/8" × 8", 19 sq ft (Unicel, 158 pleats). Pleatco: 4-5/8" × 8", 18 sq ft. | 4CH-21 |
| 20254-238 | 1-1/2" MPT. The three catalogs agree on the area. | Unicel 4CH-24. Pleatco PGS25P4. Filbur FC-0131. | 4-5/8" × 9-3/4", 25 sq ft. Unicel: 173 pleats, 3 oz. | 4CH-24 |
| 74407-98 | 1-1/2" MPT, the longest of the threaded set. Filbur’s area is not Unicel’s. | Unicel 4CH-30. Filbur FC-0141. Pleatco’s cross-reference has no 4CH-30 line. Filbur’s cell PTL25P-4 is on Pleatco’s deactivated list, sent to PSG27.5P4. | Unicel: 4-5/8" × 11-7/8", 158 pleats, 4 oz, 30 sq ft. Filbur’s Saratoga section: 27 sq ft at the same length. PSG27.5P4, the deactivated-list replacement, is 4-3/4" × 11-3/8" and 28 sq ft, and its spec line does not print 74407-98. | 4CH-30 |
| 74408-99 | 1-1/4" SAE, not MPT. Dimension One uses the same Unicel number under a different OEM. | Unicel 4CH-950. Filbur FC-0173. Filbur’s Pleatco cell PDO-UF25P2 is deactivated with replacement N/A. | Unicel: 4-5/8" × 12", 139 pleats, 25 sq ft, 1-1/4" SAE. Filbur’s length is 11-7/8". Filbur’s Saratoga section prints 27 sq ft; its size table says 25. | 4CH-950, 4CH-950 |
The square feet stored on each cartridge page are Unicel’s spec-table figures. Pleatco’s 25 sq ft and Filbur’s 15 sq ft for the short cartridge are in the notes, not averaged. Two Unicel-only rows, 74456 and 74452, are described below and are not separate cartridge pages, because no second catalog prints those OEM numbers.
The short cartridge: MPT or SAE, and 20, 25, or 15 sq ft
Filbur’s note under the Saratoga section is the fitting rule: “Factory cartridges use an adapter provided by Saratoga. Remove adapter from suction fitting before installing replacement cartridge. One fitting is SAE and other is MPT thread. Choose the correct cartridge thread to match the suction fitting.”
| What you measure | Unicel | Pleatco | Filbur Saratoga section |
|---|---|---|---|
| 6-3/4" long, 1-1/2" MPT | 20241-238 = 4CH-20, 4-5/8" × 6-3/4", 204 pleats, 20 sq ft. Spec table and price index both say 20. The Vita OEM line prints this Unicel number as PVT 25 at 25 sq ft. | PSG25P4, 4-3/4" × 6-1/2", 1-1/2" MPT, 25 sq ft, OEM 20241-238. A no-adapter twin, PSG25-XP4, is the same size and the same OEM, with a 1.90" keyed bottom. The Unicel cross-reference does not list 4CH-20. | FC-0125, 4-5/8" × 6-3/4", 15 sq ft, cell PHC25. The size table’s description says “20 sq. ft. Top Load” and its sq ft column says 25. The Vita section prints FC-0125 at 25 sq ft for OEM PVT-25. PHC25 is deactivated, replacement N/A. |
| 6-3/4" long, 1-1/4" SAE | 4CH-920, same 4-5/8" × 6-3/4" and 204 pleats, 20 sq ft. No OEM number. | No 4CH-920 line in the Unicel cross-reference. | FC-0124, 15 sq ft, cell PSG13.5. Pleatco’s PSG13.5P4 is 4-3/4" × 5-15/16" and 14 sq ft, OEM 303575, which is not on Unicel’s Saratoga list. |
Unicel’s discontinued-cartridge note for C-4303 says to use 4CH-20 when the old pad adapter is 1-1/2" MPT, and to take that adapter out of the skim well. That note is about the retired open cartridge, not a Saratoga model. The list of those replacements is in discontinued spa filter numbers. Softub’s 4CH-20 row on this site is a different claim and is still unverified: Filbur’s Softub section does not print 4CH-20.
The longer threaded cartridges
| OEM | Unicel | What else is printed |
|---|---|---|
| 20245-238 | 4CH-21, 4-5/8" × 8", 158 pleats, 19 sq ft, 1-1/2" MPT | Pleatco PTL18P4 is 18 sq ft at the same size, and the spec line also names Vita PVT-25N. Filbur FC-0121 agrees with Unicel’s 19 sq ft and 8" length. |
| 20254-238 | 4CH-24, 4-5/8" × 9-3/4", 173 pleats, 25 sq ft, 1-1/2" MPT | Pleatco PGS25P4 and Filbur FC-0131 print the same size and 25 sq ft. This is the row the three catalogs agree on. |
| 74407-98 | 4CH-30, 4-5/8" × 11-7/8", 158 pleats, 4 oz media, 30 sq ft, 1-1/2" MPT | Filbur FC-0141 is the same length and 27 sq ft. Pleatco does not cross-list 4CH-30. The PTL25 number Filbur prints is deactivated to PSG27.5P4 (4-3/4" × 11-3/8", 28 sq ft, “Saratoga Spas Circulation Pump”), and that spec line does not name 74407-98. |
| 74408-99 | 4CH-950, 4-5/8" × 12", 139 pleats, 25 sq ft, 1-1/4" SAE | Filbur FC-0173 is 11-7/8" long. The Saratoga section prints 27 sq ft; the size table says 25. The Pleatco cell PDO-UF25P2 is deactivated with replacement N/A. Dimension One’s OEM for this Unicel number is 1561-04, on the Dimension One page. |
Two OEM numbers only Unicel prints
74456 is Unicel C-4314AM: open with slots, 4-5/8" × 6", antimicrobial media, and the spec note says it needs the tabbed thread adapter already in the skim well, which Unicel does not furnish. The spec table and the price index both say 13.5 sq ft. The Saratoga OEM line prints 14. The price index also says this cartridge is not eligible to ship into Canada. Filbur’s open-slot Saratoga row, FC-0206, is 4-3/4" × 6-1/2" and 15 sq ft and does not print 74456 or C-4314AM, so it is not listed here as the same cartridge.
74452 is printed twice. Unicel’s Saratoga line lists C-4327 and C-4327AM, both 4-5/8" × 11-5/8" and both 28 sq ft, open with slots. The spec table prints only the antimicrobial cartridge, C-4327AM, at 27.5 sq ft, 158 pleats, with the same adapter note, and the price index repeats 27.5 and the Canada restriction. No plain C-4327 line turned up in the spec table or the price index. Filbur does not print 74452. There is no cartridge page for 74452 until a second catalog names it.
Where the sources disagree
- 20241-238 area. Unicel spec, price index, and the Saratoga line: 20 sq ft. Unicel’s Vita line, for PVT 25 = 4CH-20: 25. Pleatco PSG25P4: 25, and a half-inch shorter (6-1/2" against 6-3/4"). Filbur’s Saratoga section: 15. Filbur’s size table: the description says 20 and the column says 25. Filbur’s Vita section: 25.
- 4CH-920. Unicel 20 sq ft. Filbur 15, and a Pleatco cell (PSG13.5) whose own spec is a different length and a different OEM (303575).
- 20245-238. 19 sq ft in Unicel and Filbur, 18 in Pleatco. The length, 8", agrees.
- 74407-98. 30 sq ft in Unicel, 27 in Filbur’s Saratoga section. Pleatco has no 4CH-30 cross-reference line.
- 74408-99 length and area. Unicel 12" and 25 sq ft. Filbur 11-7/8", and 27 or 25 depending on which Filbur table you read.
- 74456. 13.5 sq ft in the spec table and the price index, 14 on the OEM line. No second catalog prints the OEM.
- 74452. 28 sq ft on both OEM lines. The antimicrobial spec line and the price index say 27.5. The plain C-4327 number is not in those two Unicel lists.
How to confirm yours
- If the body is about 6-3/4" long, the thread decides the cartridge. 1-1/2" MPT is 20241-238. 1-1/4" SAE is 4CH-920. Read 15, 20, and 25 as the three areas the catalogs print for that body, and compare the new cartridge with the old one.
- Take the factory adapter out before threading a replacement in, which is Filbur’s instruction, and match the replacement to the fitting that is left, not to the adapter you removed.
- Length separates the MPT series after that: about 8" is 20245-238, about 9-3/4" is 20254-238, about 11-7/8" is 74407-98. A 1-1/4" SAE cartridge near 12" is 74408-99, not 74407-98.
- An open cartridge with slots, rather than a thread, is 74456 or 74452 in Unicel only. Those two are not the threaded numbers above.
Why one length can be printed at more than one square-foot rating: the pleat-count explainer.
Why one cartridge size can carry two different square-foot ratings: our explainer with Unicel’s pleat-count table.
Sources
- Unicel 2026 Replacement Guide, Saratoga Spas OEM list, PDF p.55 (printed p.51): 20241-238 = 4CH-20 at 20 sq ft, 20245-238 = 4CH-21 at 19, 20254-238 = 4CH-24 at 25, 74407-98 = 4CH-30 at 30, 4CH-920 at 20 with no OEM, 74408-99 = 4CH-950 at 25, 74456 = C-4314AM, 74452 = C-4327 and C-4327AM at 28 sq ft
- Unicel 2026 Replacement Guide, spec table PDF p.7 (printed p.3): 4CH-20 and 4CH-920 at 4-5/8" × 6-3/4", 204 pleats, 20 sq ft; 4CH-21 at 19 sq ft; 4CH-24 at 25; 4CH-30 at 30 sq ft and 4 oz; 4CH-950 at 25 sq ft and 12"; C-4314AM at 13.5 sq ft; C-4327AM at 27.5 sq ft. Price index PDF p.81 (printed p.77): C-4314AM 13.5 sq ft and C-4327AM 27.5 sq ft, both marked not eligible to ship into Canada. Price index PDF p.88 (printed p.84): 4CH-20, 4CH-21, 4CH-24, 4CH-30, 4CH-920, and 4CH-950 at the spec-table areas.
- Unicel 2026 Replacement Guide, Vita Spas OEM list, PDF p.63 (printed p.59): PVT 25 = 4CH-20 at 25 sq ft, the same size as the Saratoga 20 sq ft line
- Pleatco 2023 Catalog, spec table PDF p.31: PSG25P4 and PSG25-XP4, OEM 20241-238, 4-3/4" × 6-1/2", 25 sq ft; PTL18P4, OEM 20245-238, 18 sq ft; PGS25P4, OEM 20254-238, 25 sq ft; PSG27.5P4, 4-3/4" × 11-3/8", 28 sq ft, Saratoga circulation pump, no 74407-98. Cross-reference PDF p.47: 4CH-21 = PTL18P4, 4CH-24 = PGS25P4; no 4CH-20, 4CH-30, or 4CH-920 line. Deactivated list: PHC25, PHC25P4, and PDO-UF25 replacement N/A; PTL25P4 replacement PSG27.5P4.
- Filbur Catalog, Saratoga Spas section, PDF p.25, including the adapter footnote: FC-0125 / 4CH-20 at 15 sq ft, FC-0124 / 4CH-920 at 15, FC-0121 / 4CH-21 at 19, FC-0131 / 4CH-24 at 25, FC-0141 / 4CH-30 at 27, FC-0173 / 4CH-950 at 27 sq ft and 11-7/8". Size table: FC-0125 described as 20 sq ft with a column of 25; FC-0173 described as 25 sq ft. Vita Spas section, PDF p.28: FC-0125 at 25 sq ft for OEM PVT-25. FC-0206 is an open-slot Saratoga row at 15 sq ft with no Unicel number.
This page summarizes published catalogs and dealer fitment tables; always follow your own spa’s owner’s manual. See our disclaimer and methodology.