Darlly 40257 Spa Filter Cartridge
Replaces Unicel 4CH-22 · Pleatco PFF25P4 (discontinued) · Filbur FC-2399
- Diameter × length
- 4-15/16" × 6-5/8"
- Filter area
- 25 sq ft
- End caps
- 2-1/8" Open / 1-1/2" male thread/MPT
- Per filter
- 1 cartridge
Pool and spa businesses in Florida, Georgia, South Carolina, Alabama, Mississippi, Louisiana and Texas order through their Grit Game rep. Everywhere else, contact Darlly Filtration directly.
Darlly 40257 is a 25 sq ft spa filter cartridge, 4-15/16" x 6-5/8". It fits the Freeflow Spas TLX, RLX. It replaces Unicel 4CH-22, Pleatco PFF25P4 (discontinued) and Filbur FC-2399.
Specifications
| Darlly part number | 40257 |
|---|---|
| Outside diameter | 4-15/16" |
| Length | 6-5/8" |
| Top end cap | 2-1/8" Open |
| Bottom end cap | 1-1/2" male thread/MPT |
| Filter area | 25 sq ft |
| Type | Spa |
| Blue antimicrobial version | 40257M |
| Darlly description | Freeflow Spas TLX, RLX |
Cross-reference
| Brand | Part numbers Darlly 40257 replaces |
|---|---|
| Unicel | 4CH-22 |
| Pleatco | PFF25P4 (discontinued) |
| Filbur | FC-2399 |
| Hurricane (former brand) | HF4H22-01 |
Older or other numbers that also point to this cartridge (not confirmed by a second source): PFF25 (Pleatco).
Filters it fits
| Filter | Cartridges per filter |
|---|---|
| Freeflow Spas TLX, RLX | 1 |
Other Darlly cartridges the same size
Same diameter and length. Check the end caps and area before swapping.
Questions
- What is the Darlly replacement for Unicel 4CH-22?
- Darlly 40257 replaces Unicel 4CH-22. Both are 4-15/16" in diameter and about 6-5/8" long.
- What Darlly cartridge replaces Pleatco PFF25P4?
- Darlly 40257 replaces Pleatco PFF25P4.
- What size is Darlly 40257?
- Darlly 40257 is 4-15/16" in outside diameter and 6-5/8" long, with 25 sq ft of filter area.
Cross-reference checked October 21, 2026 against Unicel's 2026 Replacement Guide, Pleatco's catalog (updated September 2025), filbur.com and darllyfilter.com. A competitor number is listed only when that brand's own data pairs it with the same cartridge size. Always compare the size and end caps of your old cartridge before ordering.
Brand names and part numbers are trademarks of their respective owners and are shown only to identify compatible replacements. Darlly Filtration is not affiliated with or endorsed by them. Cross-reference by The Grit Game, Darlly's sales agency.