Cloudy pool water usually comes from low sanitiser, a chemistry imbalance, or fine debris that your pool’s filtration system cannot capture or circulate away. Safety depends on clear visibility and a healthy free chlorine residual, so do not swim if you cannot clearly see the main drain or the pool floor. Fast “clear-in-an-hour” fixes can mask symptoms without fixing root causes. Use them only after you diagnose and correct the problem.
What Could Be Causing Your Cloudy Pool Water?
Most cloudy swimming pool issues trace back to three buckets: chemistry, filtration or circulation, and environmental load. Each pathway introduces or fails to remove tiny particles that scatter light and make pool water look milky or dull.
- Chemistry: Off-range free chlorine, pH, total alkalinity and calcium hardness let organics grow or minerals precipitate, both create light-scattering particles.
- Filtration or circulation: A clogged filter, an undersized sand filter or cartridge, poor proper water flow, or too little pool filter run time leaves fines in suspension.
- Environmental load: Wind, dust, pollen, sunscreen and leaves can overwhelm even a good filter.
Prioritise diagnosis in this order:
- Test the water with fresh reagents.
- Inspect the filter for media condition, check the sight glass and the pressure gauge.
- Review runtime and recent weather including wind, rain and heat.
Choosing the right filter also helps you prevent cloudy pool water in future. See Which pool filter is best.
Chemical Imbalance And Water Impurity
Keep FC, pH, TA and CH in range to stop cloudiness before it starts. Minor drifts add up. Multiple small deviations compound into noticeable haze, especially during peak UV rays and heavy bather load. Always test with fresh reagents before adjusting. Old test chemicals can make water chemistry look fine when it is not. Get accurate tools via Pool test kits.
Recommended targets for typical residential pools:
- Free chlorine (FC):
- Non-salt pools: keep FC in line with cyanuric acid (CYA), commonly 3–5 ppm at about 30–50 ppm CYA.
- Saltwater pools: 3–6 ppm with CYA 60–80 ppm is common.
- pH: 7.4–7.6, 7.2–7.8 acceptable.
- Total alkalinity (TA): 80–120 ppm, salt systems often stable closer to 70–100 ppm.
- Calcium hardness (CH): Plaster or concrete 200–400 ppm, fibreglass 175–275 ppm.
Balance with the Langelier Saturation Index in mind, since pH, TA, CH and temperature work together. Too positive increases scale which clouds water, too negative causes etching which releases fine dust.
Insufficient Free Chlorine
Low FC allows organics and microbes to multiply, turning clear water into dull or very cloudy water. Aim for enough free chlorine relative to CYA, and act if combined chlorine (CC) is greater than 0.5 ppm. If CC is high, perform a pool shock treatment to oxidise by-products and fix a cloudy pool quickly. How to do it right read: How to shock a swimming pool.
Too High pH Levels
High pH reduces chlorine efficacy and raises the risk of calcium precipitation, which creates a fine, cloudy haze. Common drivers include aeration, high TA, or overdosing soda ash. Keep pH levels between 7.4 and 7.6 and test with phenol red for accurate readings.
Improper Total Alkalinity (TA) Levels
Low TA causes unstable pH swings, and high TA encourages scale and persistent cloudiness. Target 80–120 ppm and dose in stages, then retest after full circulation. It can take up to three days to fully settle. If you need to raise TA, use an appropriate product like Alkalinity increaser and re-check pH after 24 hours.
Improper Calcium Levels
Low CH risks plaster etching, and high CH drives scale, both affect clarity. Keep CH in range for your surface and temperature. If CH is low, carefully raise using Calcium increaser. If CH is high, manage with pH and TA, and avoid high pH spikes that trigger precipitation.
Water Impurity Causes
Suspended Gunk From Swimmers
Sunscreen, cosmetics and body oils form fine emulsions that cloud water, especially after a big swim or party. Increase runtime, skim and brush, and oxidise after events. Need a hand after a party? Book a One time pool service.
Environmental Debris
Wind, leaves, dust and pollen can overwhelm filters and reduce clarity. Fit a leaf canister, empty baskets, and use the right cleaner head for your surface. Your pool brush and vacuum attachments matter. If debris is heavy, manually vacuum particles to waste to avoid cycling fines. Choosing the right cleaner helps. Start with What pool cleaner should I buy.
Chemical Contamination
Overdosing floc, metals or incompatible products can create colloids that keep water cloudy. Read labels, allow full dispersion, and avoid mixing brands mid-process. If you have overdosed chlorine or need to reset, a neutraliser helps. See Chlorine neutralizer pool testing solution.
The Weather
Heavy rain dilutes sanitiser and stirs up fine clays, heat and sun accelerate demand and can cloud a pool in a few hours. Pre-treat before storms, top up FC after rain, and run longer during heatwaves. For comfort targets by season, see Ideal swimming pool temperature for year round comfort.
Best Way To Clear A Cloudy Pool
Diagnose, then fix in this order: test and balance, clean the filter, run the pump longer, oxidise, use clarifier or floc only if needed. Clear time depends on the filtration process and severity. A clean cartridge can polish light haze overnight. A tired sand filter may take at least eight hours to a couple of days. Keep brushing so fines stay suspended for capture, and compare systems in Pool sand or cartridge filter, which is better.
Always wear personal protective equipment such as gloves and eye protection when handling chemicals.
Best Way To Clear A Cloudy Pool
Diagnose, then fix in this order: test and balance, clean the filter, run the pump longer, oxidise, use clarifier or floc only if needed. Clear time depends on the filtration process and severity. A clean cartridge can polish light haze overnight. A tired sand filter may take at least eight hours to a couple of days. Keep brushing so fines stay suspended for capture, and compare systems in Pool sand or cartridge filter, which is better.
Always wear personal protective equipment such as gloves and eye protection when handling chemicals.
Super Chlorinate The Pool
Shock with a calculated dose based on volume, current FC and CYA to oxidise organics and restore a healthy chlorine level. Brush walls, steps and the pool surface to expose biofilm and speed the kill. Keep the pump running until FC returns to target. For a simple shock option, see Shock n Swim.
Test The Water Yourself
Measure FC, CC, pH, TA and CH with fresh reagents, record results, and adjust one parameter at a time. Retest after full circulation to confirm stability. For reliable results on an average size pool, use a complete kit like Filtrite 4 in 1 pool and spa water test kit.
Clean Your Filter
Backwash sand filters until the sight glass runs clear, or clean cartridges thoroughly to restore flow. Degrease oily cartridges after parties, and inspect O-rings and laterals for damage that lets fines bypass. Full how-to here: Guide for cleaning pool filter cartridges.
Run The Pump For A Couple Of Days 24/7
Increase runtime to 24 hours until the water is visibly clear, then return to normal circulation. Verify valve positions, check the pressure gauge, and ensure proper water flow at returns. If you have a variable-speed unit, a higher speed helps polish out fines, then drop to low for economy. Guidance here: How long should a pool pump run.
Add A Clarifier Or Floc
Use a clarifier for mild haze. Use floc only for severe cloudiness when you can vacuum to waste. Never dose both together. Follow label volumes exactly and run continuously for 24 to 48 hours with clarifier. For filtration context and product ideas, see Best swimming pool filters (above-ground pools).
Pool Clarifiers
Clarifiers agglomerate tiny particles so the filter can grab them. They are ideal for light to moderate haze and cartridge systems. Allow up to 48 hours for the filter to polish the water. Clean or backwash midway if pressure rises.
Pool Floc
Floc drops particles to the floor for manual vacuum-to-waste. It is best for very cloudy water after storms or algae. Close returns if required, circulate briefly to distribute, let settle overnight, then vacuum slowly so you are not noticing dirty water coming back through returns.
What If My Pool Is Green And Cloudy?
Treat it as an algae bloom. Shock to breakpoint, brush thoroughly, and hold high FC until clear. Dead algae clogs media, so clean the filter more often and maintain circulation for up to three days if needed. Balance pH and calcium scaling risk once clear, and verify CYA so the problem does not rebound. For full service support, see Green pool recovery.
FAQs
Choose 1 Pool Care For Crystal Clear Water
Most cloudy water clears when you balance chemistry, clean the filter, and run the pump long enough to remove fines. Use a pool clarifier or floc only after root causes are fixed. Keep a weekly pool maintenance schedule, test, brush, skim and vacuum to protect chlorine levels and keep a crystal clear pool all swimming season.
If your pool still looks cloudy after the fixes above, 1 Pool Care can diagnose, treat and keep it clear all season. Our Perth technicians test on site with fresh reagents, service your filtration and circulation, and set a simple maintenance plan that suits your pool size, usage and budget.
With over 20 years of industry experience, Adrian Mole is the founder of 1 Pool Care, a leading mobile pool service in Perth. Known for his expert knowledge and reliable service, Adrian delivers professional pool cleaning, equipment repairs, and water balancing across the metro area. Backed by SPASA accreditation, he’s committed to quality, convenience, and customer satisfaction.
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