Having a filter cartridge stop working can be a huge pain. Replace your pool's current filter cartridge with a reliable option like the C-8409 Sta-Rite 11.38-Inch Replacement Filter Cartridge. This filter cartridge's part number is C8409 and measures in at 17.38 inches in length with an outside diameter of 8.94 inches. Both the top and bottom caps have 4-inch openings and in total, it has a pleat count of 174. This replacement filter cartridge works for Hayward Star-Clear Plus C900 (CX900 RE), Sta-Rite Posi Clear PXC 95 (25230 0095S), and Waterway Clearwater II 100 (817 0100N). Consider the Unicel Filter Cartridge to among your top go-to pool, hot tub, and spa cleaner essentials if you have 1 of those compatible models. However, be sure to replace your cartridge regularly to ensure the long-lasting life of your pool's filtration system. Here are some signs it may be time to replace your cartridge: The plastic end caps on your pool cartridge ensure the material stays together. They're made of heavy-duty plastic but can crack over time with exposure to pool chemicals. When they become brittle, they can crack or chip, sending broken pieces through your filtration system and causing equipment damage. Prevent any possible harm to your pool's filtering system by replacing your cartridge as soon as you notice damage on the plastic endcaps. When the pleats of your cartridge become flattened or damaged, water flow through the filter can be restricted and reduce its ability to efficiently clean your pool's water. This happens through normal use as dirt and other debris saturate the cartridge. Water pressure, chemicals, and day to day use can cause cartridges to wear over time. You may notice this in the form of ripped fabric or fraying, causing it to look like there are small "hairs" on the cartridge. If you notice ripping or tearing, replace your filter early, as these tears will only widen over time.