Every pool problem falls into one of seven categories: cloudy water, algae (green, black, or mustard), stains, scale/etching, foaming, irritation, or equipment failure. Start with the symptom, work backward to the cause, and fix the root — not the visual.
This pillar is a diagnostic tree. Find your symptom below, read the guide, and use our 5-minute triage to figure out what's actually wrong before you spend a dollar on chemicals.
Fast symptom → cause matrix
| Symptom | Most likely cause | Start here |
|---|---|---|
| Cloudy water | CYA too high, poor filtration, or dead algae | Cloudy Pool Water |
| Green tint | Chlorine too low, algae bloom starting | Green Algae Removal |
| Black spots on surface | Black algae rooted in plaster | Black Algae |
| Yellow dust on walls | Mustard algae (chlorine-resistant) | Mustard/Yellow Algae |
| Brown or blue-green stains | Metals (iron, copper) in fill water | Pool Stain Removal |
| White crust at waterline | High LSI — scale forming | Scale & Etching |
| Foaming water | Algaecide overdose or sunscreen load | Foaming Pool Water |
| Red eyes, itchy skin | Chloramines, not free chlorine | Skin & Eye Irritation |
The single biggest troubleshooting mistake
Adding more chlorine to a pool that isn't responding to chlorine. If your free chlorine reads 5 ppm and the water still looks bad, the problem isn't sanitizer level — it's usually CYA too high (neutering the chlorine), combined chlorine (chloramines) blocking new disinfection, or a filter that can't clear the water fast enough. Before dumping another bucket of shock, test everything.
When to call a pro
Green pool not clearing after 72 hours of SLAM? Black algae spreading? Stains that don't respond to ascorbic acid? That's our specialty. We bring diagnostic tools most homeowners don't own — and we'll tell you whether it's a 1-hour fix or a 3-day project before starting.