A worn-out cartridge filter element is one of the most common silent culprits behind cloudy pool water. Unlike sand or DE, cartridges can’t be backwashed — they get cleaned by hose-rinsing, then eventually replaced when the pleats lose their structure or the end caps tear. This tutorial walks through replacing a standard cartridge filter element, the same process whether you have a Pentair Clean & Clear, Hayward SwimClear, Jandy CL/CS, or Sta-Rite filter.
When to replace the cartridge
Cartridges last 2–3 years on average. Replace if you see any of these:
- You’ve hose-cleaned the cartridge and pressure still won’t drop back to baseline.
- Visible tears, holes, or separated pleats.
- The fabric is matted, slimy, or stained even after a chemical soak.
- The end caps are cracked, deformed, or pulled away from the fabric.
- It’s been more than 3 years — even an “okay”-looking cartridge filters worse than a new one at that age.
What you’ll need
- The correct replacement cartridge (we cover sizing below)
- A new filter body o-ring or band clamp gasket — always replace this when you open the filter
- Silicone-based pool lubricant for the o-ring
- A garden hose with a spray nozzle
- Channel-lock pliers (only if your band clamp is stuck — not for routine use)
Step-by-step: replacing a pool cartridge filter element
Power down at the timer or breaker. Confirm the pump is fully stopped before touching the filter.
Most cartridge filters have a small Schrader-style or twist valve on the top of the housing. Open it and listen for the hiss of pressurized air escaping. Watch the pressure gauge drop to zero. Only proceed once the gauge reads zero and no air is hissing out.
Place a bucket or hose under the drain to direct water away from the equipment pad. Open the drain plug and let the filter drain — this can take a couple of minutes.
Different filters use different closures:
- Band clamp (Pentair Clean & Clear, Hayward StarClear): loosen the bolt, lift the clamp free, and lift the upper housing straight up.
- Threaded ring (older Hayward, Jandy CL): rotate the threaded collar counter-clockwise to release.
- Bolt-on lid: remove the perimeter bolts and lift the lid.
Lift carefully — the top is heavier than it looks. Set it aside on a clean surface.
Single-element filters have one cartridge. Multi-element filters (SwimClear, CS series) have 3–7 elements arranged around a central manifold. Lift each one straight up. Some have a top plate or manifold that needs to come off first — note the orientation before you remove it so you can reinstall the same way.
Hose out the inside of the lower housing. Look for cracks, debris, or worn gaskets. Wipe down the sealing groove where the body o-ring sits. Any grit left in the o-ring groove will cause leaks on reassembly.
Drop the new cartridge straight down into the housing, lining up any locating pins or top plate keys. The cartridge should sit flat and level. Don’t force it — if it’s not going in cleanly, double-check that you have the right size and that the seat groove is clean.
This is the part most people skip. Old o-rings leak. Pull the old o-ring out of its groove, clean the groove, and seat the new one. Apply a thin film of silicone-based pool lubricant to the new o-ring before reinstalling the top.
Line up the top and lower it straight down. Reinstall the band clamp or threaded ring and tighten per the manufacturer’s spec (most band clamps are 100–120 in-lbs — about hand-tight plus 1/4 turn with a wrench).
Leave the air relief valve open and start the pump. Water will spit out the air valve as the filter fills with water and purges air. Once you see a steady stream of water with no bubbles, close the valve. Note the new clean pressure baseline on the gauge.
Common replacement cartridges
Match the new cartridge to your filter model. The most reliable way is to read the model number printed on the old cartridge before throwing it out. Common Jandy CS-series replacements (one of the most popular families):
Jandy Pro Series CS100 SF Cartridge
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Jandy Pro Series CS150 SF Cartridge
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Jandy Pro Series CS200 SF Cartridge
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Expect 2–3 swim seasons of life if you hose-clean monthly and do a deep chemical soak once per year. Cartridges that run year-round (warmer climates) wear faster than those that get a winter break. The minute you find yourself hose-cleaning more than once a month, you’re close to the end of the cartridge’s life and should plan for replacement before next season.
If you’re not sure which cartridge fits your filter, send PST Pool Supplies the filter brand and model number from the label on the housing, and we’ll match the right element the first time.