Hayward Star-Clear Plus Cartridge Filter Head O-Ring (CX900F) – 2 Pack

Hayward Star-Clear Plus Cartridge Filter Head O-Ring — part no. CX900F. This large rubber O-ring seals the filter head to the filter tank on Hayward Star-Clear Plus cartridge filters. A worn or cracked filter head O-ring causes water to leak from the joint between the filter head and the tank. Replacing this O-ring restores a watertight seal. Supplied as a 2-pack.

Compatibility

• Hayward Star-Clear Plus C751
• Hayward Star-Clear Plus C900
• Hayward Star-Clear Plus C1200
• Hayward Star-Clear Plus C1750
• Cross-reference: Sta-Rite U9-228A / O-240

Product Details

• Brand: Hayward
• Part number / SKU: CX900F
• Quantity: 2-pack
• Material: rubber

Frequently Asked Questions

How do I know if this O-ring needs replacing?

If water is leaking from the joint between the filter head and the filter tank, the filter head O-ring is the most likely cause. Turn off the pump and relieve system pressure, then remove the filter head and inspect the O-ring for cracks, flattening, or deformation. Even if the O-ring looks intact, if it has been in service for several years it may have lost its elasticity and should be replaced during routine filter servicing.

Why does this listing include 2 O-rings?

This listing supplies a 2-pack, giving you a spare for future maintenance or for use across two filters. Having a spare O-ring on hand means you can replace it immediately if the first one fails, without waiting for a new order.

Should I lubricate the O-ring when fitting it?

Yes — apply a small amount of silicone-based O-ring lubricant (not petroleum-based grease) to the O-ring before fitting. This helps the O-ring seat correctly, prevents pinching, and extends its service life.