Why Water Chemistry Matters

Maintaining proper water chemistry in your swimming pool protects both the people who swim in it and the pool itself. Imbalanced water can irritate skin and eyes, damage pool surfaces and equipment, and create an environment where bacteria and algae thrive. The good news is that once you understand the basics, maintaining pool chemistry becomes a straightforward routine.

The Core Parameters to Monitor

1. pH Level

pH measures how acidic or alkaline the water is on a scale of 0–14. The ideal range for swimming pool water is 7.2 to 7.6.

  • Too low (acidic): Corrodes metal components, irritates eyes and skin, degrades pool surfaces.
  • Too high (alkaline): Causes scale buildup, reduces chlorine effectiveness, leads to cloudy water.

Use pH increaser (sodium carbonate) to raise it, or pH decreaser (sodium bisulfate or muriatic acid) to lower it.

2. Chlorine

Chlorine is the primary sanitiser that kills bacteria, viruses, and algae. The ideal free chlorine level is 1–3 parts per million (ppm). Test chlorine at least twice a week during swimming season.

3. Total Alkalinity (TA)

Total alkalinity acts as a buffer for pH, preventing rapid fluctuations. The recommended range is 80–120 ppm. Low alkalinity makes pH unstable; high alkalinity makes pH hard to adjust.

4. Calcium Hardness

This measures the amount of dissolved calcium in the water. Aim for 200–400 ppm. Low calcium causes water to draw minerals from pool surfaces (etching); high calcium leads to scale deposits.

5. Cyanuric Acid (Stabiliser)

Cyanuric acid protects chlorine from being degraded by UV sunlight. For outdoor pools, a level of 30–50 ppm is typically recommended. Too high can reduce chlorine's effectiveness.

Testing Your Pool Water

There are several ways to test your pool water:

  1. Test strips: Quick and inexpensive. Dip the strip in the water and compare colours to the chart. Good for regular monitoring.
  2. Liquid test kits: More accurate than strips. Add reagent drops to a water sample and compare the resulting colour.
  3. Digital testers: The most accurate option for home use. Provide precise numerical readings.
  4. Professional testing: Many pool supply shops offer free water testing. Useful for seasonal opening/closing or when troubleshooting a persistent problem.

A Simple Weekly Maintenance Routine

  • Test pH and chlorine 2–3 times per week
  • Test total alkalinity and calcium hardness weekly
  • Add chemicals as needed, following manufacturer instructions and dosing guidelines
  • Run the pump and filter for the recommended number of hours each day
  • Shock the pool (add a large dose of chlorine) every 1–2 weeks or after heavy use

Safety When Handling Pool Chemicals

Pool chemicals are effective because they're powerful — handle them with care:

  • Always add chemicals to water, never water to chemicals
  • Never mix different chemicals together before adding to the pool
  • Wear gloves and eye protection when handling concentrated products
  • Store chemicals in a cool, dry place away from children and out of direct sunlight

Consistent testing and small, regular adjustments are far easier to manage than trying to correct a severely imbalanced pool. Start with a reliable test kit, check your water regularly, and you'll spend more time swimming and less time troubleshooting.