AQUALTRA Spa Filter 5 x 9.25 in PRB35-IN Compatible 2-Pack — Washable, High-Capture

AQUALTRA's 5" x 9 1/4" PRB35-IN-compatible spa filter 2-pack provides reusable, NSF-certified cartridge filtration for hot tubs and spas that fit PRB35-IN, C-4335, FC-2385 and similar models.

Keep your spa water clearer and your system running smoothly with these replacement cartridges designed to match popular OEM sizes. Constructed from durable, BPA-free materials and engineered for improved particle capture, each cartridge is washable and built to resist chemicals commonly found in pool and spa water. The pair offers a practical spare so you can swap while one is cleaning, helping maintain regular filtration without downtime.

How does this filter capture more debris than a standard cartridge?

These AQUALTRA cartridges use a high-surface-area PET composite fabric and a reinforced core to trap fine particles that ordinary filters may let pass. The design emphasizes layered filtration and a tight pleat structure to hold hair, lint, sand and sediment until rinsed away.

• Dirt-locking PET composite fabric for improved particle retention
• 35 square feet of effective filtration area per cartridge
• Reinforced polypropylene core to maintain shape under flow
• High chlorine-resistant end caps for longer life in treated water

Will this filter fit my hot tub or spa model?

Measure your existing cartridge to confirm fit: these replacements are 5 inches in outer diameter and 9 1/4 inches long, with a 2 1/8 inch opening top and bottom. They are made to be compatible with many common OEM part numbers, but you should always verify dimensions match your unit before ordering.

• Outer diameter: 5 inches; length: 9 1/4 inches
• Top and bottom opening: 2 1/8 inches
• Compatible with PRB35-IN, C-4335, FC-2385, Waterway 35 and others
• Check your current filter’s measurements and part number for confirmation

How do I clean and maintain these AQUALTRA cartridges?

These cartridges are designed to be rinsed and reused—regular cleaning restores flow and filtration efficiency. Remove the filter from your spa before cleaning, gently rinse with a hose, and periodically soak in a filter-cleaning solution for a deeper clean; allow it to dry before reinstalling if recommended by your cleaning product.

• Rinse every two weeks under a steady water stream
• Use a filter-specific cleaner for heavy soil or oily residues
• Remove filter prior to any chemical shock or corrosion-prone cleaning
• Rotate filters: keep one in use while the other is cleaned and drying

What safety and quality standards apply to these replacement cartridges?

AQUALTRA builds these cartridges from BPA-free plastics and NSF/ANSI-certified materials to ensure they resist common spa chemicals and provide safe operation. The end caps and core are selected for chemical tolerance and structural stability, reducing premature breakdown and minimizing contamination risk from degraded parts.

• BPA-free materials with NSF/ANSI certification for safety
• High chlorine-resistant end caps to limit chemical wear
• Durable core to prevent collapse under pump pressure
• Manufactured as aftermarket replacements; verify compatibility

Who is this for? If you own a hot tub or spa that uses PRB35-IN-sized cartridges—or a compatible model like C-4335, FC-2385, Dynamic Series 03FIL1300 or Waterway 35—this AQUALTRA 2-pack is for you. It's suited to homeowners and service technicians who need dependable, reusable filtration without OEM price tags, and for anyone who prefers to keep a spare filter on hand for uninterrupted spa use. Always confirm your current filter’s dimensions and part number before purchase to ensure correct fit and performance.