Cloudy, green, smelly, irritating: symptom to fix
When something looks off, this page gets you from symptom to solution fast. The pattern almost never changes: test the water, fix the chemistry, and keep the pump running. Reach for shock and clarifier only when the numbers say so.
Match the symptom, check the likely cause, then act. Almost every pool problem traces back to chemistry or circulation, so test first and let the pump run.
| Symptom | Likely cause | What to do |
|---|---|---|
| Cloudy or hazy water | Low or zero FC, high pH, poor filtration, high CH, fine debris | Test and restore FC to target, lower pH to 7.2 to 7.8, run the pump 24/7, clean or backwash the filter, add clarifier only if needed. |
| Green water (algae) | FC dropped too low, sunny warm spell, low CYA letting chlorine burn off | Brush thoroughly, shock to the SLAM-level FC for your CYA and hold it, run pump 24/7, vacuum dead algae to waste, keep FC up until water clears. |
| Eye and skin irritation | pH off (too low or high), high combined chlorine (CC), not low chlorine | Test pH and bring to 7.2 to 7.8, check CC. If CC is above 0.5, shock to breakpoint. Irritation usually means imbalance, not too much chlorine. |
| Strong chlorine smell | High combined chlorine (chloramines), not enough free chlorine | Counterintuitive but true: shock the pool. Raise FC to breakpoint to burn off chloramines, then the smell clears. |
| Chlorine will not hold | CYA too low (no UV protection) or too high (locks chlorine), or organic load | Test CYA. If under 30, raise stabilizer. If very high, dilute by draining and refilling. Shock and keep FC at the target for your CYA. |
| pH keeps climbing | High TA, fresh plaster, aeration from features or salt cell | Lower TA toward 60 to 80 with acid and aeration, then maintain pH with small muriatic acid doses. |
| Scale or white crust | High CH and/or high pH and TA | Lower pH and TA into range. If CH is well above 400, partially drain and refill with softer water. |
| Stains on the surface | Metals in water (iron, copper) or organic debris | Identify metal vs organic with a stain test. Use a sequestrant for metals, ascorbic acid for stains, and keep leaves out. |
| Foamy water | Algaecide overdose, low CH, or cosmetics and oils from bathers | Stop adding algaecide, check CH is at least 200, and let the filter run. Foam usually settles on its own. |
| Short filter cycles / high psi | Dirty filter, fine debris load | Backwash or clean the filter when psi rises 8 to 10 over baseline. Replace worn cartridges or old sand/DE as needed. |
Your pool's recurring issues and the fix that worked, so next season you skip straight to the solution.
Always test before dosing and add chemicals in steps, retesting between additions. Dosing and range figures are estimates from standard pool-care formulas and are not a substitute for testing your own water. Educational only. Always follow the product label and local guidance.