Rainbow Dynamic 50 (spa) replacement filter cartridge

Looking for a replacement cartridge for a Rainbow / spa Rainbow Dynamic 50 (spa)? The compatible Pleatco part is PRB50-IN, which cross-references to Unicel C-4950 and Filbur FC-2390. Check the specs below against your old cartridge, then compare prices.

Cross-reference

Sources: Pleatco Catalog & Cross Reference Guide, Leslie’s and retailer product listings. Always compare the length, outside diameter and center openings of your old cartridge before ordering: manufacturers revise parts, and similar-looking cartridges differ by fractions of an inch.

How to confirm the fit

1. Find the model name on your filter tank’s label, or the part number printed on the end cap of the old cartridge.
2. Measure the old cartridge: overall length (end cap to end cap), outside diameter, and the openings at top and bottom (open hole, closed, or handle).
3. Match all three to the specs above. See how to measure a filter cartridge.

When to replace it

Spa cartridges work hard in hot water: most need a rinse every 1-2 weeks, a chemical soak every month or so, and replacement about every 12-24 months depending on use. See when to replace a filter cartridge.

Cleaning between replacements

Rinse with a garden hose from top to bottom, working between the pleats; soak in a filter cleaner periodically to remove oils and scale. Never use a pressure washer: it damages the fabric. Full guide: how to clean a hot tub filter cartridge.