🧭Troubleshooting cheat sheet
What Chemical Fixes What
Symptom to cause to the lever that actually moves it.
Symptom → lever
| You see / measure | Likely cause | The lever |
|---|---|---|
| pH too high | Normal upward drift, aeration | Muriatic acid or dry acid (use pH calculator) |
| pH too low | Acid overdose, rain, rich fills | Soda ash to raise pH |
| Alkalinity high | Fill water, over-dosing | Muriatic acid, aerate to recover pH |
| Alkalinity low | Acidic water, dilution | Baking soda |
| Chlorine won't hold | Low CYA, high demand, or lock | Check CYA; shock to breakpoint |
| Green / cloudy water | Algae, low FC | SLAM: raise and hold FC, filter, brush |
| Scaling / cloudy from balance | High LSI (scale-forming) | Lower pH/alkalinity (LSI calculator) |
| Etching / corrosion | Low LSI (aggressive) | Raise CH / alkalinity (LSI calculator) |
| Calcium hardness high | Hard fill water | Partial drain and refill |
Fix the underlying number, then re-test. Chase one parameter at a time.
Note: Free chlorine and pH doses depend on other numbers (CYA and alkalinity). Use the calculators for exact amounts rather than a fixed cup measure.
General reference for residential pools. Product labels and local guidance override any figure here. See our methodology and editorial policy. Skimmer · skimmer pool care.