Listing we opened and checked. Match the diameter, length and both fittings on this page before you order. The price is on Amazon; we do not print one.
Arctic Spas OEM PRT-115LOT spa filter (C-4950)
Arctic Spas (Unicel lists Arctic under Blue Falls Mfg. Ltd., Canada)
Replacement numbers
Unicel C-4950, Pleatco PRB50-IN
Fits Arctic Spas OEM PRT-115LOT.
Diameter 4-15/16" (125 mm)Length 13-5/16" (338 mm)50 sq ft1 model listedUnicel C-4950
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| Unicel | C-4950 |
|---|---|
| Pleatco | PRB50-IN |
| Filbur | FC-2390 |
| Top | 2-1/8" (54 mm) / open |
| Bottom | 2-1/8" (54 mm) / open |
Bottom: 2-1/8" (54 mm) / open
Drawn to scale from the listed diameter and length and open-end sizes. Handles, threads and closed ends are drawn as symbols, not to scale. 50 sq ft media.
Arctic Spas (Unicel lists Arctic under Blue Falls Mfg. Ltd., Canada) is the group name on the Arctic Spas row C-4950 cartridge. Match these numbers: OEM PRT-115LOT; Unicel C-4950; Pleatco PRB50-IN; Filbur FC-2390. 4-15/16" across, 13-5/16" long, top 2-1/8" / open, bottom 2-1/8" / open, 50 sq ft.
What the sources add about PRT-115LOT: Unicel has no Arctic table of its own and says "see Blue Falls Mfg. Ltd. (Canada)"; Filbur lists this part under both Arctic Spas and Blue Falls Mfg. Arctic Spas Ontario sells the factory 50 sq ft pleated drop-in filter as PRT-115LOT and says it matches C-4950, PRB50-IN and FC-2390, for Arctic and most Coyote spas built in 2008 or earlier. The same dealer says these open-core cartridges do not fit the threaded intake used from 2009.
Hot tubs named for PRT-115LOT: Arctic Spas and most Coyote spas (drop-in filter), years 2008 or earlier, listed by Arctic Spas Ontario dealer listing (factory pleated PRT-115LOT, 50 sq ft).
Left blank on purpose: factory part number from one Arctic dealer only; Arctic's owner's manual gives no part numbers; other dealers date the drop-in era 1998-2008 and exclude the Marmot model from the disposable drop-in.
Where those figures are printed: Unicel 2026 Replacement Guide on C-4950 (OEM cross reference: Arctic Spas entry (PDF p.28, printed p.24) points to Blue Falls Mfg. Ltd. (Canada), PDF p.29 (printed p.25); spec table PDF p.9 (printed p.5)). Pleatco 2023 Catalog on C-4950 (Unicel-to-Pleatco cross reference, PDF p.47 (C-4950 = PRB50-IN); Filbur prints this as PRB50-/-MIN). Filbur Catalog & Reference Guide on C-4950 (Product by Pool/Spa Manufacturer (OEM), Arctic Spas, printed p.27 (PDF p.14)). Arctic Spas Ontario (dealer) on C-4950 (Filter 50 Pleated Drop-In: PRT-115LOT, 50 sq ft, = C-4950 / PRB50-IN / FC-2390, Arctic and most Coyote spas 2008 or earlier).
Hot tubs listed for this cartridge
The rest of the Arctic Spas model list is the Arctic Spas filter by model and year lookup.
| Model / system | Years | Listed by |
|---|---|---|
| Arctic Spas and most Coyote spas (drop-in filter) (factory pleated PRT-115LOT, 50 sq ft) | 2008 or earlier | Arctic Spas Ontario dealer listing |
Check the cartridge you removed
Measure diameter, length, and both ends, then compare them with the figures above. The steps are in the measuring guide. Why the bottom decides whether it seals: open-end vs threaded filters. Power, the retainer, and not running the spa empty: how to install a cartridge. Number formats: how Filbur, Unicel and Pleatco numbers compare.
The same C-4950 number is also on the Caldera, Jacuzzi, Sundance, Beachcomber, Coleman Spas pages.
Every number on this row, on one screen: cross-reference lookup. Published clean and replace intervals for this cartridge, and a buy link for the numbers above: replacement schedule and reorder. The interval comparison by brand: calculator.
Cleaner and test strips
Hose rinse and soak steps are in how to clean a cartridge. Named cleaners and strips are in filter cleaners and test strips.
Filter cleaner and test strips
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Leisure Time O Filter Clean Cartridge Cleaner Listing title: cartridge cleaner, 32 fl oz.
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SpaGuard Filter Cleaner Listing title: filter cleaner for spas and hot tubs, 1 quart.
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AquaChek SPA 6-in-1 Test Strips Listing title: reads total bromine, total chlorine, free chlorine, pH, total alkalinity and total hardness.
Unicel C-4950 Listing we opened and checked. Match the diameter, length and both fittings on this page before you order. The price is on Amazon; we do not print one.
Sources
- Unicel 2026 Replacement Guide: OEM cross reference: Arctic Spas entry (PDF p.28, printed p.24) points to Blue Falls Mfg. Ltd. (Canada), PDF p.29 (printed p.25); spec table PDF p.9 (printed p.5) (PDF)
- Pleatco 2023 Catalog: Unicel-to-Pleatco cross reference, PDF p.47 (C-4950 = PRB50-IN); Filbur prints this as PRB50-/-MIN (PDF)
- Filbur Catalog & Reference Guide: Product by Pool/Spa Manufacturer (OEM), Arctic Spas, printed p.27 (PDF p.14) (PDF)
- Arctic Spas Ontario (dealer): Filter 50 Pleated Drop-In: PRT-115LOT, 50 sq ft, = C-4950 / PRB50-IN / FC-2390, Arctic and most Coyote spas 2008 or earlier (web page)
Not in sources: factory part number from one Arctic dealer only; Arctic's owner's manual gives no part numbers; other dealers date the drop-in era 1998-2008 and exclude the Marmot model from the disposable drop-in.