PCD50N / C-7350 / FC-3963
50 sq ft replacement filter cartridge • 7″ OD × 10.75″ long
Caldera's Paradise Series tubs (the Kauai, Martinique, and Cumberland built from 2003 on) use this 50-square-foot cartridge with open 7-inch-diameter ends. Caldera's own part numbers are 73532, 1019401, and X268330, and it crosses cleanly to Unicel C-7350 and Filbur FC-3963. Caldera is a Watkins Wellness brand, sister to Hot Spring, but don't assume the filters swap between them. The Paradise cartridge is its own size. If your Caldera is a larger Utopia-series tub instead, you probably need the taller PCD75N or the handle-top PCD100W, so match the length of your old element, not just the diameter.
Compare on Amazon
PCD50N replacements on Amazon
The buttons below pull up Amazon results for each cross-reference part number. Same physical cartridge, different stickers, often different prices. Cross-shop and pick the cheapest option that has solid recent reviews.
Cross-Reference & Interchangeable Part Numbers
| Brand | Part Number | Type |
|---|---|---|
| Pleatco | PCD50N | Primary |
| Unicel | C-7350 | Equivalent |
| Filbur | FC-3963 | Equivalent |
| OEM | Caldera 73532 | Original Equipment |
| OEM | Caldera 1019401 | Original Equipment |
| OEM | Caldera X268330 | Original Equipment |
Always verify dimensions and end-cap type before purchasing a replacement.
Compatible Hot Tubs & Spas
The PCD50N (or any of its cross-references) fits these spa models. Cartridge sizing occasionally shifted between model years, so it's worth confirming against your owner's manual or the cartridge label.
Frequently Asked Questions
What are the dimensions of the PCD50N?
The PCD50N is 7 inches in outer diameter, 10.75 inches long, with an open top and an open bottom. Total filtration area is 50 square feet. Before ordering, pull your existing cartridge and measure it yourself, or check the label inside the housing. OD and length both have to match within about an eighth of an inch, and the end-cap style needs to match exactly so the cartridge seats properly when the lid closes.
What other part numbers are interchangeable with the PCD50N?
PCD50N is the same physical cartridge as C-7350, FC-3963, plus OEM versions like Caldera 73532, Caldera 1019401, Caldera X268330. Same dimensions (7" × 10.75"), same open top, same open bottom. The Pleatco, Unicel, and Filbur boxes ship the same media inside, just with different stickers. The only thing to watch is the end-cap style: if a cross-reference has a slightly different cap design, it may not seat right in your housing.
Is the Caldera 73532 the same filter as the PCD50N?
Yes. Caldera 73532 is an OEM number, the code the tub or pool builder stamps on the cartridge they ship. The filter itself is made by Pleatco, Unicel, or Filbur, so Caldera 73532 (along with Caldera 1019401, Caldera X268330) and PCD50N, C-7350, FC-3963 all point to one interchangeable cartridge. Buy whichever is cheapest with solid recent reviews, and just check that the dimensions match your old cartridge before you order.
How often should I replace the PCD50N?
Mid-size spa cartridges like the PCD50N (50 sq ft) usually last 12 to 24 months. It shows up most often in Caldera tubs. The real driver is use: a tub that gets daily soaks for a couple of people burns through cartridges about twice as fast as one used a few times a month. A good rhythm is a monthly hose rinse, a deep soak in cleaner at every water change (every three to four months), and replacement once the pleats tear, the seams stain brown, or a soak no longer brings post-clean pressure back to baseline.
How do I clean the PCD50N?
The PCD50N has open ends on both top and bottom, so water flows straight through. Pull the cartridge from the housing and hose it down. Hit the pleats from above at about a 45-degree angle so water rinses debris out instead of packing it deeper, and work top to bottom while rotating the cartridge. Skip the pressure washer. The high pressure tears or collapses pleats, and once that happens you've lost media that doesn't come back. Every few months (or at every water change, whichever comes first), do a deep clean: overnight soak in a hot tub filter cleaner, then a thorough rinse. If your cartridge has a closed end cap, let it dry before reinstalling so you don't trap moisture inside the cartridge core.
Which hot tubs and spas use the PCD50N?
The PCD50N is compatible with: Caldera Kauai, Caldera Makena. Confirm against your owner's manual or the label inside the filter compartment, since some brands changed cartridge sizing between model years.
Dimensions
Specifications
| Outer Diameter | 7″ |
|---|---|
| Length | 10.75″ |
| Top Type | Open (no end cap) |
| Bottom Type | Open (no end cap) |
| Filtration Area | 50 sq ft |
| Primary Brand | Pleatco |
| Part Number | PCD50N |
Fitment notes
Caldera Paradise Series Kauai, Martinique, Cumberland 2003+.