Pool Chemistry Guide

Keeping your pool water balanced is key to a safe and enjoyable swimming experience. Learn how to manage pH, alkalinity, and sanitizers the right way.

Understanding Pool Chemistry

Your pool’s water is more than just H2O—it contains a mix of chemicals that need to be kept in balance. If levels go too high or too low, your water can turn cloudy, become irritating to swimmers, or even damage pool equipment.

  • pH Balance (7.2 - 7.8): Keeps water comfortable and prevents equipment damage.
  • Alkalinity (80 - 120 ppm): Helps stabilize pH and prevents fluctuations.
  • Chlorine (1 - 3 ppm): Kills bacteria and prevents algae growth.
  • Calcium Hardness (200 - 400 ppm): Prevents plaster damage and scaling.
  • Cyanuric Acid (30 - 50 ppm): Protects chlorine from UV rays in outdoor pools.

How to Test Your Pool Water

Regular testing helps maintain the right chemical balance and prevents problems before they start. The best ways to test pool water include:

  • Test Strips: Quick and easy but less precise.
  • Liquid Test Kits: More accurate, commonly used by pool professionals.
  • Digital Testers: High precision but more expensive.

Adjusting Pool Chemistry

If your test results show unbalanced levels, here’s how to correct them:

  • Low pH? Add sodium carbonate (soda ash) to raise it.
  • High pH? Add muriatic acid or sodium bisulfate to lower it.
  • Low chlorine? Use liquid chlorine or chlorine tablets.
  • High chlorine? Let the sun break it down naturally or use sodium thiosulfate.
  • Low alkalinity? Add baking soda.
  • High alkalinity? Use muriatic acid, but add it gradually.

When and Why to Shock Your Pool

Shocking your pool removes contaminants and restores sanitizer levels. You should shock your pool:

  • After heavy use (e.g., pool parties)
  • After a rainstorm that dilutes chemicals
  • If you notice cloudy or green water
  • If chlorine levels are low despite regular treatment

Use calcium hypochlorite (Cal-Hypo) for routine shocks or non-chlorine shock for quick boosts.

Common Pool Chemistry Mistakes to Avoid

  • Overusing chemicals: More isn’t always better; overdosing can cause irritation and damage equipment.
  • Not testing frequently enough: A weekly test helps maintain balance before problems arise.
  • Ignoring calcium hardness: Too low, and plaster erodes; too high, and scaling occurs.
  • Adding chemicals at the wrong time: Always adjust pH first, and wait before adding other treatments.

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