Universal Spa Filter C-4950/PRB50-IN/RD50

Compare the dimensions of your current filter with these specifications:
– Length: 338 mm (13.31 inch)
– Diameter: 127 mm (5 inch)
– Connection:
 • Top: closed
 • Bottom: fine internal thread (SAE), 1.5 inch (± 38 mm internal diameter)

If your old filter is marked with C-4950, PRB50-IN, RD50, or a combination of these, then this filter is a suitable replacement. Commonly used in medium-sized spas from brands such as Passion Spas, Waterway, and Cal Spas.

Not sure? Send us a photo or the measurements of your old filter – we are happy to assist you further.

On average, you replace a spa filter every 2 to 3 months for optimal water quality and proper operation of your spa. Even with regular cleaning, a filter eventually becomes saturated with dirt, oils, and lime.

How do you know it's time to replace your filter?

Watch for the following signs:
• The filter remains dirty despite thorough cleaning
• The material is damaged (cracks, frays, or deformation)
• The water remains cloudy or has an unpleasant odor
• The water flow decreases
• Your pump makes more noise or works harder than usual

If you use your spa frequently or with multiple people, it may be necessary to replace the filter more often than every 3 months. For those who want certainty, it's smart to keep a spare filter in stock and alternate regularly.