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Parts for your model · verified 2026-07-03
Replacement parts for the Universal 50 sq ft drop-in spa cartridge (PRB50-IN)
The exact compatible parts we've verified fit this model. Guaranteed fit
| Brand | Universal |
|---|---|
| Model | 50 sq ft drop-in spa cartridge (PRB50-IN) |
| Typical use | Most hard-shell hot tubs — DROP-IN (no thread), 50 sq ft. The industry workhorse. |
| Also known as | PRB50-IN, C-4950, FC-2390, 817-5000, 6540-471, Rainbow Dynamic |
Compatible parts
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FAQ
What replacement filter fits the Universal 50 sq ft drop-in spa cartridge (PRB50-IN)?
It uses 817-5000 / 6540-471 (Replacement Spa Cartridge — Compatible with Pleatco PRB50-IN / Unicel C-4950 / Filbur FC-2390 (50 sq ft drop-in)). Our compatible version matches that fit and carries a fit guarantee.
How often should I change the part on a Universal 50 sq ft drop-in spa cartridge (PRB50-IN)?
Typical replacement is Change every 4 months, sooner in dusty or pet homes.