Darlly 40191 Spa Filter Cartridge
Replaces Unicel 4CH-21 · Filbur FC-0121
- Diameter × length
- 4-5/8" × 8"
- Filter area
- 19 sq ft
- End caps
- Handle / 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 40191 is a 19 sq ft spa filter cartridge, 4-5/8" x 8". It fits the Pageant top load and Dream Maker, Vita, Hydro, Maax, Saratoga. It replaces Unicel 4CH-21, Filbur FC-0121 and Saratoga Spas 20245-238.
Specifications
| Darlly part number | 40191 |
|---|---|
| Outside diameter | 4-5/8" |
| Length | 8" |
| Top end cap | Handle |
| Bottom end cap | 1-1/2" male thread/MPT |
| Filter area | 19 sq ft |
| Type | Spa |
| Blue antimicrobial version | 40191M |
| Darlly description | top load |
Cross-reference
| Brand | Part numbers Darlly 40191 replaces |
|---|---|
| Unicel | 4CH-21 |
| Filbur | FC-0121 |
| Hurricane (former brand) | HF4H21-01 |
| OEM and other numbers | Saratoga Spas 20245-238 |
Older or other numbers that also point to this cartridge (not confirmed by a second source): PTL18P (Pleatco), PSI18 (Pleatco).
Filters it fits
| Filter | Cartridges per filter | OEM cartridge number |
|---|---|---|
| Pageant top load; Dream Maker, Vita, Hydro, Maax, Saratoga (19 sq ft filter) | 1 | 20245-238 |
Filbur FC-3029 crosses to 42518 (25 sq ft).
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-21?
- Darlly 40191 replaces Unicel 4CH-21. Both are 4-5/8" in diameter and about 8" long.
- What size is Darlly 40191?
- Darlly 40191 is 4-5/8" in outside diameter and 8" long, with 19 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.