Winterize/close a commercial pool per MAHC/manufacturer guidance

Steps

1. Follow the pool equipment manufacturer's specific winterization instructions first, since heater, pump, and automation procedures vary significantly by make and model.
2. Balance and shock water chemistry before closing, consistent with the operating jurisdiction's adopted code guidance, to reduce algae/scale growth during the off-season.
3. Lower the water level as appropriate for the pool type and blow out/drain lines as needed to prevent freeze damage in applicable climates.
4. Cover the pool with a code-compliant safety/winter cover where locally required, and secure electrical equipment/breakers per manufacturer and local electrical code guidance.
5. Document the closing date, final chemistry readings, and steps taken, since many health departments require a documented closing (and a fresh inspection before reopening).