PRB50-IN / C-4950 / FC-2390
50 sq ft replacement filter cartridge • 5″ OD × 13.3125″ long
The PRB50-IN is one of the most cross-referenced cartridges in the spa world, which is why you'll see it under a pile of different part numbers: Jacuzzi 373045, Waterway 817-5000, Caldera 73533, Unicel C-4950, Filbur FC-2390. They're all the same 50-square-foot drop-in with open 2-1/8-inch ends. It's the standard filter for the Jacuzzi J-200 series from 2005 on (the J-210 through J-275) and the Caldera Oasis from 2002 to 2009. Because so many brands spec it, it's one of the easier cartridges to shop on price. The generic boxes are frequently a fraction of what the Jacuzzi-branded one costs for identical media. Just confirm your tub is a 2005-or-later J-200 first, since earlier tubs used a different size.
Compare on Amazon
PRB50-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 | PRB50-IN | Primary |
| Unicel | C-4950 | Equivalent |
| Filbur | FC-2390 | Equivalent |
| OEM | Jacuzzi 373045 | Original Equipment |
| OEM | Jacuzzi 373045J | Original Equipment |
| OEM | Guardian 413-212-02 | Original Equipment |
| OEM | Waterway 817-5000 | Original Equipment |
| OEM | Caldera 73533 | Original Equipment |
Always verify dimensions and end-cap type before purchasing a replacement.
Compatible Hot Tubs & Spas
The PRB50-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.
Frequently Asked Questions
What are the dimensions of the PRB50-IN?
The PRB50-IN is 5 inches in outer diameter, 13.3125 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 PRB50-IN?
PRB50-IN is the same physical cartridge as C-4950, FC-2390, plus OEM versions like Jacuzzi 373045, Jacuzzi 373045J, Guardian 413-212-02, Waterway 817-5000, Caldera 73533. Same dimensions (5" × 13.3125"), 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 Jacuzzi 373045 the same filter as the PRB50-IN?
Yes. Jacuzzi 373045 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 Jacuzzi 373045 (along with Jacuzzi 373045J, Guardian 413-212-02, Waterway 817-5000, Caldera 73533) and PRB50-IN, C-4950, FC-2390 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 PRB50-IN?
Mid-size spa cartridges like the PRB50-IN (50 sq ft) usually last 12 to 24 months. It shows up most often in Jacuzzi 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 PRB50-IN?
The PRB50-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 PRB50-IN?
The PRB50-IN is compatible with: Jacuzzi J-210, Jacuzzi J-220, Jacuzzi J-230, Jacuzzi J-235, Jacuzzi J-245, Jacuzzi J-275, Caldera Oasis. 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 | 13.3125″ |
| Top Type | Open (no end cap) |
| Bottom Type | Open (no end cap) |
| Filtration Area | 50 sq ft |
| Primary Brand | Pleatco |
| Part Number | PRB50-IN |
Fitment notes
2-1/8 inch open top and bottom. Drop-in. Jacuzzi J-200 series 2005+, also Caldera Oasis 2002-2009.