Unicel C-4975 – 75 sq ft Replacement Cartridge

Product Overview

The Unicel C-4975 is a high-quality replacement cartridge filter designed for spa and pool systems. With approximately 75 square feet of pleated polyester media, it offers excellent debris capture and flow performance for compatible filter tanks.

Key Features

• 75 sq ft of filtration area to handle heavier loads and extend cleaning intervals.
• Durable polyester media combined with a reinforced core and end caps for repeated use and rinsing.
• Precision dimensions: Outside diameter ~4-15/16", length ~20-1/8", and inner diameter ~2-1/8" (open both ends).
• Direct replacement for a variety of cartridge filter models from several manufacturers.

Technical Specifications

• Part Number: C-4975
• Square Feet: ~75 sq ft
• Outside Diameter: ~4-15/16” (~125.4 mm)
• Length: ~20-1/8” (~511 mm)
• Inner Diameter (both ends): ~2-1/8” (~54 mm), open end style
• Pleat Count: ~210 pleats

Applications & Compatibility

This cartridge is suitable for use in many spa and pool systems where the original cartridge specified a 4-15/16" diameter and 20-1/8” length with open ends. Its large filtration area and reliable construction make it a good choice for replacing worn cartridges in commercial or high-usage residential systems.

Installation Instructions

• Turn off the pump and relieve pressure from the filter system before opening the tank.
• Remove the old cartridge, clean the filter tank interior and inspect for signs of wear or damage.
• Insert the new C-4975 cartridge, ensuring it is correctly seated and the open ends are properly aligned with the filter tank ports.
• Reassemble the filter tank, restore power and pump operation, then monitor pressure and flow to confirm proper installation.

Troubleshooting & Tips

• High pressure on start-up: Verify that the cartridge pleats are fully expanded and not compressed or bent.
• Reduced flow: Check for debris build-up in pleats; rinse cartridge thoroughly or consider replacement if media is damaged.
• Leaks or bypass in tank: Ensure the cartridge only fits one orientation (open ends match tank ports) and that the tank lid or closure is sealed correctly.

Maintenance Tip

For best results, rinse the cartridge monthly (or more often in heavy use or high debris systems) and schedule replacement every 12-18 months or when the pleats show a permanent discoloration or damage. Keeping the cartridge clean and replacing at the appropriate interval helps maintain water clarity, system efficiency, and prolongs pump and heater life.