PCD75N / C-7375 / FC-3964
75 sq ft replacement filter cartridge • 7″ OD × 14.75″ long
The PCD75N is the taller cousin of the PCD50N. Same 7-inch diameter, but nearly 15 inches long for 75 square feet of media. It fits later Caldera Paradise tubs and the early Utopia Series (2003-2004) models like the Palermo, Montclair, and Niagara. Caldera numbers it 73531 and 1019301, and the equivalents are Unicel C-7375 and Filbur FC-3964. Since it shares a diameter with the shorter PCD50N, length is the giveaway. Measure your old cartridge end to end before you order. Drop a 10-3/4-inch element into a housing built for a 14-3/4-inch one and you'll leave a gap that water simply bypasses.
Compare on Amazon
PCD75N 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 | PCD75N | Primary |
| Unicel | C-7375 | Equivalent |
| Filbur | FC-3964 | Equivalent |
| OEM | Caldera 73531 | Original Equipment |
| OEM | Caldera 1019301 | Original Equipment |
Always verify dimensions and end-cap type before purchasing a replacement.
Compatible Hot Tubs & Spas
The PCD75N (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 PCD75N?
The PCD75N is 7 inches in outer diameter, 14.75 inches long, with an open top and an open bottom. Total filtration area is 75 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 PCD75N?
PCD75N is the same physical cartridge as C-7375, FC-3964, plus OEM versions like Caldera 73531, Caldera 1019301. Same dimensions (7" × 14.75"), 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 73531 the same filter as the PCD75N?
Yes. Caldera 73531 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 73531 (along with Caldera 1019301) and PCD75N, C-7375, FC-3964 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 PCD75N?
75 sq ft is a lot of media for a hot tub, so the PCD75N tends to outlast the small-format spa cartridges. It shows up most often in Caldera tubs. Two adults soaking a couple times a week can usually get 18 to 24 months out of one. Monthly hose rinses and a quarterly overnight soak stretch that further. Replace it when the pleats won't rinse clean or pressure starts climbing in a way soaking can't fix.
How do I clean the PCD75N?
The PCD75N 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 PCD75N?
The PCD75N is compatible with: Caldera Palermo, Caldera Montclair, Caldera Niagara. 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 | 14.75″ |
| Top Type | Open (no end cap) |
| Bottom Type | Open (no end cap) |
| Filtration Area | 75 sq ft |
| Primary Brand | Pleatco |
| Part Number | PCD75N |
Fitment notes
Caldera Paradise Series 2003+, Utopia Series 2003-2004 (Palermo, Montclair, Niagara).