Is your pool water cloudy, green, or just not filtering like it used to? You’re likely dealing with a filter problem. Pool filters are essential to clean, safe swimming—but when they fail, problems stack up fast. Whether you have a sand, cartridge, or DE filter, this guide breaks down the most common swimming pool filter issues and how to fix them without calling in a pro.
Why Pool Filters Matter More Than You Think
Your pool’s filter is its first line of defense against dirt, algae, and debris. Even with proper chlorine levels, without efficient filtration, your water quality will decline fast. But filters aren’t foolproof. Over time, they clog, leak, or break down—causing cloudy water, poor circulation, and system strain.
1. Low Filter Pressure
What causes low pressure in the filter system?
Low pressure often points to an obstruction before the filter—usually in the skimmer, pump basket, or suction line.
Direct Answer: Low filter pressure happens when water isn’t reaching the filter due to clogged baskets, blocked pipes, or air leaks in the suction line.
Fixes:
- Check and clean the skimmer and pump baskets.
- Inspect suction lines for clogs or air leaks (look for air bubbles in the pump).
- Ensure the pool water level is high enough to feed the skimmer properly.
Recommended Product:
Poolmaster Pool Skimmer Basket with Handle – Easy to remove and clean. A simple upgrade that prevents clogs and improves water flow.
2. High Filter Pressure
Why is the pressure gauge reading too high?
This is a sign that your filter media is dirty or there’s a blockage after the filter.
Direct Answer: High pressure usually means the filter is dirty, the return line is blocked, or the backwash valve is partially closed.
How to fix it:
- Backwash the filter if you have a sand or DE system.
- Clean or replace cartridges in cartridge systems.
- Inspect the return jets and valves for obstructions or misalignment.
Recommended Product:
Swimables Filter Cartridge Cleaner Spray – Penetrates deep into filter pleats to remove oils, debris, and buildup quickly.
3. Cloudy Pool Water Despite Filter Running
Why is the water still dirty?
Even with the filter on, cloudy water often points to poor filtration media, improper chemical balance, or insufficient run time.
Direct Answer: If your water stays cloudy, your filter may be undersized, dirty, or running for too short a time per day.
Solutions:
- Run the filter 8–12 hours daily during swim season.
- Make sure your pump and filter are properly sized for your pool volume.
- Shock the pool and use a clarifier to boost filtration temporarily.
Recommended Product:
Clorox Pool&Spa Super Water Clarifier – Binds fine particles so your filter can remove them easily. Safe for all filter types.
4. Leaks Around the Filter or Pump
What causes filter leaks?
Leaks usually occur at o-rings, seals, or valves. Over time, rubber gaskets can dry out or crack, leading to water loss and reduced efficiency.
Direct Answer: Leaks form when o-rings wear out or fittings loosen, allowing water to escape from the pump or filter housing.
How to fix it:
- Inspect o-rings on the pump lid and filter tank—replace if cracked or misshapen.
- Use silicone lubricant to seal new o-rings properly.
- Tighten unions and clamps to manufacturer specs (not too tight—avoid damage).
Recommended Product:
Aladdin Magic Lube Silicone Lubricant – Perfect for pool o-rings and gaskets, water-resistant and long-lasting.
5. Filter Not Catching Fine Debris
Why is dirt still settling on the floor?
If your pool still looks dirty after hours of filtration, your media might be the problem.
Direct Answer: Filters fail to catch fine debris when the media is old, dirty, or not rated for small particle filtration.
How to improve filtration:
- Upgrade sand filters with glass media for better performance.
- Replace old or damaged cartridges with higher-efficiency models.
- Add DE powder to sand filters for finer filtration.
Recommended Product:
ZeoSand Alternative Filter Media – Replaces traditional sand, captures smaller particles, and reduces backwashing frequency.
6. Backwash Valve Problems
Why won’t the filter backwash properly?
Multiport valves and backwash lines can jam or leak, leading to ineffective cleaning or even damage to your filter system.
Direct Answer: Backwashing problems occur when the valve handle is worn, the gasket is damaged, or the line is blocked.
Fix it like this:
- Disassemble the multiport valve and inspect the spider gasket.
- Clean or replace the gasket and re-lubricate all moving parts.
- Flush the backwash line to remove debris or clogs.
Recommended Product:
Hayward Multiport Valve Tune-Up Kit – Includes new gaskets, seals, and lubricant to restore proper valve function.
7. Air Bubbles in Return Jets
Why is air getting into the system?
Bubbles coming from return jets usually mean air is leaking into the suction side of your pump system.
Direct Answer: Air bubbles are caused by leaks in the suction line, pump lid, or low water level in the skimmer.
Quick fix:
- Check that the pump lid o-ring is clean, lubricated, and sealed tight.
- Inspect the skimmer for vortexing—top off the pool if water is too low.
- Tighten all suction-side fittings and check for cracks in the pump housing.
Recommended Product:
U.S. Pool Supply Lid O-Ring Seal Replacement – Prevents air leaks and maintains prime in the pump system. A fast fix for bubbling issues.
8. Broken or Cracked Filter Tank
Can filter tanks crack?
Yes, especially if they’re over-pressurized, exposed to harsh weather, or made of older plastic.
Direct Answer: Cracks in the filter tank can result from freeze damage, over-tightened bands, or years of UV exposure.
What to do:
- Inspect the tank for hairline cracks and replace if leaking under pressure.
- Avoid overtightening clamps or lids—follow torque specs.
- Use a cover to shield equipment from sun and weather.
Recommended Product:
Pool Equipment Cover by The Pool Boss – Waterproof, UV-resistant, and designed to extend the life of your filter and pump.
Seasonal Pool Filter Maintenance Checklist
- Spring: Deep clean the filter and check all gaskets before starting up.
- Summer: Backwash or rinse weekly, clean cartridges monthly, and inspect pressure levels regularly.
- Fall: Clean out falling debris frequently and monitor flow rates as temps drop.
- Winter: Blow out lines and drain filter if you’re closing your pool for the season.
Conclusion: Stay Ahead of Pool Filter Problems
Most pool filter issues can be fixed with simple maintenance and a few affordable parts. Whether you’re dealing with low pressure, dirty water, or leaky seals, the key is knowing what to look for—and acting fast. Keep your pool sparkling, safe, and swim-ready by inspecting your filter system weekly and using the right tools for the job.
Ready to upgrade or troubleshoot your system? Start with the recommended products listed above to extend the life of your filter and enjoy hassle-free swimming all season long.