Top 10 common pool problems — and how to fix them
Reviewed by the GTA Pool Contractors editorial teamLast reviewed How we research
Choose a problem
What is your pool doing?
Each guide covers the signs, the usual causes, an ordered fix and the weekly habits that keep the problem from coming back.
Water clarity
Green pool water
A green pool is usually an algae bloom, not simply a filter problem. Clear it with brushing, balanced water, the right shock level for your stabilizer and 24/7 filtration.
Find the fixWater clarity
Cloudy pool water
Cloudy water is usually a filtration or chemistry issue. Test first, clean the filter, correct pH and sanitizer, then give the filter time before reaching for clarifier.
Find the fixWater loss
Losing water
Evaporation is normal; a steady drop above a quarter inch a day is worth testing. The bucket test separates evaporation from a leak before you pay for detection.
Find the fixChemistry
pH out of balance
High pH makes chlorine lazy and encourages scale; low pH corrodes equipment and irritates swimmers. Test total alkalinity before adding a pH adjuster.
Find the fixChemistry
Low chlorine
Chlorine that reads zero or disappears overnight usually means demand is outpacing the dose, stabilizer is too high or the feeder is not delivering.
Find the fixChemistry
Chlorine smell
The public-pool smell is usually combined chlorine, not a high free chlorine reading. Test both before adding more chlorine or reaching for a neutralizer.
Find the fixEquipment
High filter pressure
A filter gauge 8–10 psi above its clean baseline usually means restricted flow. Clean the right component for your filter type before assuming the pump is failing.
Find the fixEquipment
Pump not moving water
A pump that will not prime usually has low water, a suction air leak, a clogged basket or a closed valve. Turn the power off before inspecting anything.
Find the fixEquipment
Heater not heating
Most heater failures start with low water flow, a gas supply issue or an ignition fault. Check flow and the error code, but do not open the gas side yourself.
Find the fixSurfaces
Stains and scale
A stain is a chemistry clue. Identify whether it is organic, metal or scale before treating it; the wrong product can set the stain or damage the liner.
Find the fixBefore you dose
Take four readings first.
Pool problems often look alike at the surface. These four readings narrow the cause before you change the chemistry. Write the numbers down so you can see a trend instead of guessing from one test.
Free and combined chlorine
Free chlorine does the work; combined chlorine is the spent portion that causes the sharp smell.
pH and total alkalinity
These decide whether chlorine can work and whether the water will scale or corrode.
Stabilizer (CYA)
Too little burns off in sunlight; too much holds chlorine back from doing its job.
Filter pressure and flow
Compare the gauge with its clean baseline, then look at the strength of the returns.
If you use test strips, confirm a persistent problem with a drop test. Chemical doses depend on your pool volume; use the product label or a dose calculator rather than a generic scoop.
Still not sure what is wrong?
Send the symptom, your city and the readings you have. We will point you toward the right local repair or service option — no obligation.