Winterizing a Pool in Arizona — Why You Don't Close, but Here's What You Do
AZ pools don't close like northern pools — but winter chemistry, pump runtime, and freeze protection still matter. Here's the November-to-March playbook.
Don't close — adjust
Phoenix winters rarely freeze hard enough to require closing. You keep the system running, adjust runtimes, and protect against the 3–5 hard-freeze nights per year.
Pump runtime
Drop from 8 hr summer / 6 hr spring to 4 hr winter. Save $40–$80/month on electricity.
Freeze protection
Enable freeze protection on automation (kicks pump on at ~38°F to prevent line freeze). If no automation, set timer to override and run continuously on forecast freeze nights. Open all valves so water keeps moving.
Chemistry
Cold water holds chlorine longer — you'll use less. Algae growth slows but doesn't stop. Test weekly instead of every 2–3 days. Lower salt cell output ~20%.
Heater
Gas heater: drain header during freeze nights if not heating. Heat pump: shuts itself off below ~50°F (won't heat efficiently). Pool covers cut nightly heat loss 50%+.
