Work through these in order
Most pump and filter issues have a handful of usual suspects. Before assuming the worst, work through the checks below in order — the fix is often simpler than it looks from the symptom alone.
Symptom: Pump won't prime, or keeps losing prime
Likely cause: Air is getting into the system somewhere before the pump — usually a low water level, an air leak at a suction-side fitting, or a dirty skimmer/pump basket restricting flow.
Check first: water level (should sit mid-skimmer), then the pump basket and skimmer basket for debris, then the lid O-ring on the pump for a proper seal. A hairline crack in suction-side plumbing can also pull air in without an obvious leak on the outside.
Symptom: Pump turns on and off repeatedly (short cycling)
Likely cause: Usually overheating (poor airflow around the motor, or it's simply too hot) or a failing capacitor/motor issue on older pumps.
Check first: that nothing is blocking airflow around the pump housing, and that it's not running in direct, extreme heat without any shade or ventilation. If airflow is fine and it's still cycling, that's usually a job for a technician rather than a DIY fix.
Symptom: Filter pressure gauge keeps creeping up
Likely cause: The filter media (sand, cartridge, or DE) is dirty and restricting flow — this is completely normal and expected over time.
Check first: your filter type's normal cleaning process — backwash for sand filters, rinse or replace for cartridges, recharge for DE. As a rough guide, clean when pressure reads 8–10 PSI above the clean, freshly-backwashed baseline — the exact number varies by system, so that baseline reading matters more than any single number. If the gauge itself isn't moving at all, see our pressure gauge troubleshooting guide.
Symptom: Weak flow or low suction at the skimmer
Likely cause: Something is restricting flow somewhere in the system — a clogged basket, a dirty filter, a partially closed valve, or air getting into the suction side.
Check first: baskets, then filter pressure (see above), then confirm all valves are fully open. If flow is still weak after all of that, it's worth checking for a blockage in the plumbing itself.
Symptom: Pump is noisy — grinding, screeching, or loud humming
Likely cause: Grinding or screeching usually points to a worn bearing; loud humming without the pump actually turning often means the motor is struggling to start (a capacitor issue) or something's jammed on the impeller.
Check first: whether the pump shaft turns freely by hand when off (never test this while it's running or plugged in). A pump making these noises is usually near the end of its life or needs a part replaced — this is generally a call-a-professional situation rather than a DIY one.
Symptom: Water stays cloudy even though the filter is running fine
Likely cause: This is very often a water chemistry problem, not an equipment problem — imbalanced pH/alkalinity, or a sanitiser level that's too low to keep up with bather load or heat.
Check first: test and balance the water before assuming the equipment is at fault. If chemistry is genuinely fine and it's still cloudy, then look at filter run time (it may just need to run longer) and filter media condition.
When it's time to call a professional
Anything involving electrical work, a motor that's making grinding or screeching noises, or a problem that persists after working through the checks above is worth a proper inspection rather than continued troubleshooting. Chasing a mechanical fault with chemicals, or a chemistry problem by replacing parts, tends to cost more than just getting the right diagnosis first.