Testing your pool water

Testing the pool water is the most important regular care task, for the health and enjoyment of your swimmers and the longevity of your pool.
  •  For help with a specific question, you can call our free helpline at 1-800-SOS-POOL (767-7665)
Frequency Ideal rangeParts per million (ppm)
Total alkalinity, plastered pools Every  month 80 - 120 ppm
Total alkalinity,  vinyl, painted or fiberglass pools Every month 125 - 150 ppm
pH level of water Every other day 7.2 - 7.6
Free chlorine Every other day 1 - 3 ppm
Stabilizer-conditioner (cyanuric acid) Start and middle of season Minimum 30 ppm with tabs; minimum 75 ppm with liquid
Shock treatment Every 7 to 10 days 5 - 10 ppm
Water hardness Seasonally 100 - 500 ppm
Drain and refill pool 5-7 years

Some easy hints

  • Test with a clean and accurate kit and fresh agents (replace kit annually)
  • The best time to test is early evening
  • Circulate water before testing
  • Do not take a sample next to return inlets
  • For maximum chlorine effectiveness, run pump at night when pool is not being used
  • Take samples 18 inches below the surface
  • Hold clean test vials upside down and push down in water
  • Measure carefully; the lowest point of a sample must meet the fill-line on the test vial
  • Add reagent drops to test water while holding the reagent bottle straight upside down
  • Do not cover test vials with fingers
  • Read results against a white background
  • Pour test residue into the water after testing, to oxidize test reagents
Always follow instructions for each test