When to Replace a Pool Filter: Signs & Solutions

Your pool filter is the workhorse behind clean, clear water. But even with regular cleaning, all filters wear out eventually. Knowing when to replace a pool filter can save you from cloudy water, algae outbreaks, and unnecessary chemical use.

In this guide, we explain:

The signs your filter is no longer working properly
How long different filter types last
What to check before replacing
How to choose the right replacement

How Long Do Pool Filters Last?

The average lifespan depends on the filter type:

Filter Type	Lifespan
Cartridge	2–5 years
Sand	5–7 years
Glass Media	7–10 years
Zeolite	5–7 years

These numbers vary based on:

How often you clean it
Water chemistry
Pool size and usage
Environmental debris (dust, leaves)

Signs You Need to Replace Your Pool Filter

✅ 1. Water Is Cloudy Despite Regular Maintenance

If your water remains cloudy after shocking and balancing chemicals, the issue may be the filter. A worn-out filter can’t trap fine debris or dead algae properly.

✅ 2. Pressure Gauge Readings Are Abnormal

Consistently high pressure (25+ psi) after cleaning may indicate internal blockage
No pressure build-up even when dirty could signal damage or bypassing

If backwashing or cleaning doesn’t reset the gauge — it’s likely time for a replacement.

✅ 3. Cartridge Is Fraying or Torn

For cartridge filters:

Check for ripped pleats
Frayed edges
Collapsed centre cores

Even a small tear lets dirt and algae through. Once damaged, the cartridge needs replacing — cleaning won’t help.

✅ 4. Sand or Glass Is Channelled or Compacted

Sand and glass filters can develop “channels” over time, where water flows through without filtration.

Symptoms include:

Short filter cycles
Water returning dirty after backwash
Fine dust in the pool

If you haven’t changed the media in 5–7 years, it’s likely due.

✅ 5. Filter Housing or Laterals Are Cracked

Inspect the inside of your filter tank:

Look for cracks in plastic parts
Broken laterals (in sand filters)
Warped cartridges

Damaged internal parts reduce efficiency and may leak sand or water into the pool.

✅ 6. Pump Runs Constantly but Water Quality Declines

If you’re running your pump longer but still fighting green or cloudy water, your filter could be failing.

Overworked filters:

Struggle to remove fine particles
Let debris recirculate
Increase chemical demand

✅ 7. Frequent Backwashing Doesn’t Help

Backwashing should restore normal pressure and flow. If it doesn’t:

Media may be clogged beyond recovery
The filter could be undersized for your pool

If backwashing every few days, rather than weeks, it’s a red flag.

Cartridge vs Sand/Glass Media Filters — When to Replace

Cartridge Filters

Replace when:

The material is fraying, tearing, or stained
Flow rate drops even after cleaning
You’ve used it for 3–5 full seasons

Tip: Rotate between two cartridges to extend lifespan.

Sand or Glass Media Filters

Replace media when:

Water looks dusty or hazy
Backwashing no longer clears pressure
Media is 5–7 years old
Pool has had algae outbreaks

If your filter tank itself is leaking or cracked — the whole unit may need replacement.

What to Do Before Replacing

Clean thoroughly first (don’t rely on appearance)
Check pump is working correctly
Verify water chemistry (poor balance can mimic filter issues)
Check pressure gauge for accuracy

Still not filtering properly? Time for new gear.

Explore cartridges, media, and filters in our pool products section.

Choosing the Right Replacement Filter

Key factors:

Pool volume (litres)
Filter type (cartridge, sand, glass)
Pipe and pump compatibility
Desired maintenance level (cartridges are easier but cleaned more often)

Ask our team or shop by size and brand via our pool products.

Conclusion

Don’t let an old or clogged filter ruin your pool water.
Know when to replace a pool filter by watching for:

Cloudy water
High pressure
Damaged cartridges
Poor backwash results

A new filter or fresh media can restore your pool to crystal clear in just a few days.

Need help choosing the right fit? Visit our pool products or talk to our team in-store.

FAQ

How often should I replace my pool filter?

It depends on the type. Cartridge filters last 2–5 years, while sand or glass filters need new media every 5–7 years. Replace sooner if performance drops.

Why is my water still cloudy after cleaning the filter?

Your filter may be worn out or undersized. If cleaning and chemicals don’t work, it’s likely time to replace the filter or media.

How do I know if my filter cartridge is bad?

Look for tears, frayed material, discolouration, or weak flow after cleaning. If any of these apply, replace it — cleaning won’t fix damage.

How can I tell if sand or glass media needs replacing?

Signs include short filter cycles, dusty water, and ineffective backwashing. If it’s been more than 5 years, consider replacing the media.

What happens if I don’t replace a worn filter?

Dirty or broken filters let algae, dust, and bacteria back into the water. You’ll use more chemicals and risk cloudy or unsafe water.

Should I replace the whole filter or just the media?

If the tank is intact, you can usually just replace the media. But if the housing is cracked or leaking, replace the entire filter unit.

Can I use glass media instead of sand?

Yes. Glass media lasts longer, filters finer particles, and backwashes more efficiently. It’s a great upgrade from standard sand.