Doule King PRB25 Spa Filter Replacement — 2 Pack for PRB25-IN & 5x13 Drop-In (C-4326, FC-2370/2375)

Overview

The Doule King PRB25 spa filter replacement is designed to fit standard 5x13 drop-in cartridges, delivering a dependable path to clear water and consistent spa performance. Built to align with widely used cartridge sizes, this replacement offers a straightforward, ready-to-use option for hot tub filtration without the guesswork.

With careful construction and precise sizing, it supports regular spa cycles by maintaining smooth water flow and trapping particulates during filtration. The result is a balanced feel and a more enjoyable soak experience, derived from a filter that integrates into your routine rather than complicates it.

Technical specs

• Length: 13 5/16 inches; Outside Diameter: 5 inches; Top / Bottom Opening: 2 1/8 inches; Filtration Area: 25 sq ft
• Easy to release trapped debris during cleaning, returning the cartridge to close-to-new filtration performance after a rinse
• Replaces For Unicel C-4326, Pleatco PRB25-IN, Filbur FC-2375, FC-2370; compatible with 5x13 drop-in spa filters
• Sold as a 2-pack, providing ready replacements and better value for ongoing spa care

Why this filter matters

• Large filtration area (25 sq ft) supports efficient particulate capture and steady water flow
• Routine maintenance becomes easier when the cartridge is designed for simple cleaning and quick reinsertion
• Cross-compatibility with common models helps reduce fitting concerns during replacement shopping

Maintenance and care

For best results, clean the cartridge every 2 weeks, rinse thoroughly, and allow it to dry before reinstalling. Regular, light maintenance helps preserve flow and water quality across spa cycles.

What you get

This listing provides a 2-pack of PRB25 spa filters, designed for convenient, ongoing replacement that fits a wide range of popular hot tubs.