PWK30V / C-5431 / FC-3910 / Watkins 31233
30 sq ft replacement filter cartridge • 5″ OD × 10.375″ long
Compare on Amazon
PWK30V 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 | PWK30V | Primary |
| Unicel | C-5431 | Equivalent |
| Filbur | FC-3910 | Equivalent |
| OEM | Watkins 31233 | Original Equipment |
Always verify dimensions and end-cap type before purchasing a replacement.
Frequently Asked Questions
What are the dimensions of the PWK30V?
The PWK30V is 5 inches in outer diameter, 10.375 inches long, with an open top and an open bottom. Total filtration area is 30 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 PWK30V?
PWK30V is the same physical cartridge as C-5431, FC-3910, plus OEM versions like Watkins 31233. Same dimensions (5" × 10.375"), 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 Watkins 31233 the same filter as the PWK30V?
Yes. Watkins 31233 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 Watkins 31233 and PWK30V, C-5431, FC-3910 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 PWK30V?
Most filter cartridges last between 12 and 24 months. Pull the PWK30V every few months for a hose rinse, soak it in cleaner quarterly, and replace it when the pleats are torn, channeling, or won't come clean. Bather load, water chemistry, and how often you actually clean it all matter more than the calendar.
How do I clean the PWK30V?
The PWK30V 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 PWK30V?
Pull your existing cartridge and read the part number off the end cap, or check the label inside the filter compartment. That's the most reliable way to confirm compatibility.
Dimensions
Specifications
| Outer Diameter | 5″ |
|---|---|
| Length | 10.375″ |
| Top Type | Open (no end cap) |
| Bottom Type | Open (no end cap) |
| Filtration Area | 30 sq ft |
| Primary Brand | Pleatco |
| Part Number | PWK30V |
Fitment notes
For Hot Spring FH and IH 220V models. Unicel lists the equivalent C-5431 at 5-1/8 by 10-1/4 inches against Pleatco's 5 by 10-3/8, so measure your housing if the fit is tight. Replaces Watkins OEM 31233.