Darlly 81004 Spa Filter Cartridge
Replaces Unicel C-8399 · Pleatco PCD100W · Filbur FC-3965
- Diameter × length
- 8" × 16-1/2"
- Filter area
- 100 sq ft
- 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 81004 is a 100 sq ft spa filter cartridge, 8" x 16-1/2". It fits the Caldera 100 (Utopia, Elation, Aspire 2005+). It replaces Unicel C-8399, Pleatco PCD100W, Filbur FC-3965, Caldera 1039607 and Caldera 73722.
Specifications
| Darlly part number | 81004 |
|---|---|
| Outside diameter | 8" |
| Length | 16-1/2" |
| Filter area | 100 sq ft |
| Type | Spa |
| Blue antimicrobial version | 81004M |
| Darlly description | Caldera |
Cross-reference
| Brand | Part numbers Darlly 81004 replaces |
|---|---|
| Unicel | C-8399 |
| Pleatco | PCD100W |
| Filbur | FC-3965 |
| Hurricane (former brand) | HF8399-01 |
| OEM and other numbers | Caldera 1039607, Caldera 73722 |
Filters it fits
| Filter | Cartridges per filter | OEM cartridge number |
|---|---|---|
| Caldera 100 (Utopia, Elation, Aspire 2005+) (100 sq ft filter) | 1 | 1039607, 73722 |
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 C-8399?
- Darlly 81004 replaces Unicel C-8399. Both are 8" in diameter and about 16-1/2" long.
- What Darlly cartridge replaces Pleatco PCD100W?
- Darlly 81004 replaces Pleatco PCD100W.
- What size is Darlly 81004?
- Darlly 81004 is 8" in outside diameter and 16-1/2" long, with 100 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.