PRB35-IN / C-4335 / FC-2385 / Pentair 17-2482 / Pentair R173431 / Caldera 74148
35 sq ft replacement filter cartridge • 5″ OD × 9.25″ long
Compare on Amazon
PRB35-IN 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 | PRB35-IN | Primary |
| Unicel | C-4335 | Equivalent |
| Filbur | FC-2385 | Equivalent |
| OEM | Pentair 17-2482 | Original Equipment |
| OEM | Pentair R173431 | Original Equipment |
| OEM | Caldera 74148 | Original Equipment |
| OEM | Waterway 817-3501 | Original Equipment |
| OEM | Sundance 6000-136 | Original Equipment |
| OEM | Custom Molded Products 25393 | Original Equipment |
| OEM | Aber Hot Tubs 03FIL1300 | Original Equipment |
Always verify dimensions and end-cap type before purchasing a replacement.
Compatible Hot Tubs & Spas
The PRB35-IN (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.
| Brand | Model |
|---|---|
| Sundance | Tacoma 680 |
Frequently Asked Questions
What are the dimensions of the PRB35-IN?
The PRB35-IN is 5 inches in outer diameter, 9.25 inches long, with an open top and an open bottom. Total filtration area is 35 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 PRB35-IN?
PRB35-IN is the same physical cartridge as C-4335, FC-2385, plus OEM versions like Pentair 17-2482, Pentair R173431, Caldera 74148, Waterway 817-3501, Sundance 6000-136, Custom Molded Products 25393, Aber Hot Tubs 03FIL1300. Same dimensions (5" × 9.25"), 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 Pentair 17-2482 the same filter as the PRB35-IN?
Yes. Pentair 17-2482 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 Pentair 17-2482 (along with Pentair R173431, Caldera 74148, Waterway 817-3501, Sundance 6000-136, Custom Molded Products 25393, Aber Hot Tubs 03FIL1300) and PRB35-IN, C-4335, FC-2385 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 PRB35-IN?
Mid-size spa cartridges like the PRB35-IN (35 sq ft) usually last 12 to 24 months. It shows up most often in Sundance 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 PRB35-IN?
The PRB35-IN 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 PRB35-IN?
The PRB35-IN is compatible with: Sundance Tacoma 680. 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 | 5″ |
|---|---|
| Length | 9.25″ |
| Top Type | Open (no end cap) |
| Bottom Type | Open (no end cap) |
| Filtration Area | 35 sq ft |
| Primary Brand | Pleatco |
| Part Number | PRB35-IN |
Fitment notes
2-1/8 inch open top and bottom. In-line cartridge for Pentair Rainbow Dynamic 35 and Dynamic Series IV DFM/DFML filters. Used by Caldera (74148), the Sundance Tacoma 680 (6000-136), Waterway 35 sq ft top-load housings, and Custom Molded Products top-mount skim filters. Both cross-reference sheets also file it under Bullfrog Spas.