My Pool Is Green, Cloudy, or Won't Clear Up
Since 2005, building and rescuing pools in Arizona, this is the single question I get asked most: 'David, my pool turned green overnight — what do I do?' The answer is almost never just 'shock it.' Green and cloudy are two different problems with two different fixes, and Arizona's sun, dust, and calcium make both worse than they'd be anywhere else. — David Bell, Founder, AE Outdoor Living · President, Southwest Hardscapes Association
- Free chlorine dropped below 1 ppm — algae bloomed in under 24 hours (common after monsoon, parties, or a tripped pump).
- High phosphates from dust, fertilizer runoff, or fill water feeding the bloom even when chlorine is technically present.
- Cyanuric acid (stabilizer) above 80 ppm, which locks up your chlorine in the desert sun.
- Filter is clogged, undersized, or the cartridges are at end of life — you cannot clear cloudy water with a dirty filter.
- Calcium hardness out of range — Arizona fill water is hard and pushes pools toward scaling and cloudiness on its own.
- Pump runtime too short for summer heat — most AZ pools need 8–12 hours/day in July, not 6.
- Dumping a bucket of liquid chlorine in and hoping.
- Pool-store 'shock and clarifier' combo with no water test.
- Brushing once and walking away.
- Backwashing the filter and assuming that's enough.
- Shocking a pool with 100+ ppm stabilizer barely raises usable chlorine — you'll burn money on chemicals that do nothing.
- Clarifier makes cloudy water look better for a day, then it comes back because the underlying cause (filter, phosphates, balance) wasn't fixed.
- Brushing without circulation just moves algae around — it re-attaches within hours.
- DE and cartridge filters need full cleans (not just backwash) to clear a bloom — backwash alone leaves the bridge for algae intact.
- Full water panel first — free chlorine, combined chlorine, pH, alkalinity, calcium, CYA, phosphates. No guessing.
- If CYA is over 80 ppm: partial drain and refill before any chemical work. Otherwise you're burning chlorine for nothing.
- Phosphate remover when phosphates are over 500 ppb — kills the food source before the chlorine fight starts.
- Proper shock dose calculated against your stabilizer level (not the back-of-the-bag number), then 24-hour circulation.
- Filter teardown and chemical clean — not just a backwash. Replace cartridges if they're past their service life.
- Pump schedule rebuilt for AZ summer reality and your equipment — variable-speed pools usually run longer at lower RPM.
- DIY green-to-clean chemicals typically run $80–$250 if the filter is healthy and stabilizer is in range.
- Professional green-to-clean service in Phoenix typically runs $300–$700 including water testing, chemicals, and filter clean.
- If a partial drain is required (high CYA or TDS), add $150–$400 depending on pool size.
- Equipment-driven causes (failing pump, undersized filter, no automation) are a separate scope — we'll quote that honestly.
Why did my pool turn green overnight?+
Free chlorine dropped below the level needed to hold off algae — usually because the pump tripped, a storm dumped organics in, or stabilizer is so high that the chlorine you have isn't actually working. In Arizona summer, an unprotected pool can bloom in 12–24 hours.
Why is my pool cloudy after I shocked it?+
Three usual culprits: (1) the filter can't catch the dead algae fast enough — clean or replace cartridges; (2) calcium hardness is high and the shock pushed pH up, causing calcium to fall out of solution; (3) you shocked over a high-phosphate, high-CYA pool and the chlorine never reached effective levels. Cloudy after shock is normal for 24–48 hours if circulation is good.
How do I get rid of pool algae fast in Arizona?+
Test water first. Lower stabilizer if it's over 80 ppm. Add a phosphate remover. Hit the pool with a calculated shock dose based on your actual CYA. Brush all walls and steps. Run the filter 24 hours straight and clean cartridges when pressure rises 8–10 psi over clean baseline.
Will shocking a green pool always work?+
No. If cyanuric acid is over ~100 ppm, shock barely moves the needle — your chlorine is chemically locked. A partial drain to bring CYA back into 30–50 ppm range is required first. This is the single biggest mistake AZ homeowners make.
How long should I run my pool pump in Phoenix?+
Most Phoenix-area pools need 8–12 hours per day from May to September, and 6–8 hours October to April. Variable-speed pumps usually run longer at low RPM for the same energy cost. If yours has been running 4 hours a day, that's likely part of why algae keeps coming back.
Should I call a pool service or fix it myself?+
If you can read a test strip, swap cartridges, and you have time to babysit it — DIY is fine for a moderate bloom. Call a pro when: the pool has been green more than a week, you can't see the second step, the filter is older than 10 years, or you've shocked it twice and it's still green. That usually means stabilizer or equipment is the real problem.