How to balance pool water chemistry step by step

Why Balancing Your Pool Water Chemistry is Essential

As a pool owner in New Zealand, maintaining properly balanced pool water is key to ensuring a safe and enjoyable swimming experience. Incorrect water chemistry can lead to issues like algae growth, cloudy water, and even skin irritation. Plus, poorly balanced water can damage your pool surface and equipment over time.

Below is a step-by-step guide to help you keep your pool water crystal clear and safe for swimming.

Step 1: Test Your Pool Water

Before adding any chemicals, it’s important to test your water to understand what needs adjusting. You can use test strips, liquid test kits, or a digital tester to measure key chemical levels.

Key Chemical Levels to Test For:

pH (7.2 – 7.6) – Ensures water is comfortable for swimmers and prevents equipment corrosion.
Total Alkalinity (80 – 120 ppm) – Helps stabilise pH levels.
Calcium Hardness (180 – 250 ppm for most pools) – Prevents scaling and surface damage.
Chlorine (1 – 3 ppm) – Kills bacteria and keeps water sanitised.
Cyanuric Acid (Stabiliser) (30 – 50 ppm) – Protects chlorine from breakdown by sunlight.

You can purchase pool testing kits from Bunnings NZ or Para Rubber. Many local pool shops also offer free in-store water testing.

Step 2: Adjust the pH Level

The pH of your pool water affects all other chemical balances.

If pH is too low (below 7.2): Add Sodium Bicarbonate (pH Up) to increase it.
If pH is too high (above 7.6): Add Sodium Bisulfate (pH Down) or Hydrochloric Acid to lower it.

You can find pH adjusters at stores like The Warehouse or specialised pool supply shops like Pools & Spas Warehouse NZ.

Step 3: Balance Total Alkalinity

Total alkalinity acts as a buffer for pH. If alkalinity is too low, pH can fluctuate wildly.

To increase alkalinity: Add Baking Soda (Sodium Bicarbonate).
To decrease alkalinity: Add Hydrochloric Acid (Muriatic Acid) or Sodium Bisulfate.

Make sure to adjust alkalinity before rechecking the pH.

Step 4: Maintain Sanitiser Levels (Chlorine)

Chlorine is essential for killing bacteria and maintaining clean water.

If chlorine levels are too low (below 1 ppm): Add pool chlorine granules, liquid, or tablets.
If chlorine is too high (above 5 ppm): Allow the sun to naturally break it down, or use a chlorine neutraliser.

For automated chlorine management, consider installing a chlorinator from Pool & Spa Warehouse NZ.

Step 5: Check and Adjust Cyanuric Acid (Stabiliser)

Cyanuric Acid (CYA) helps stabilise chlorine, especially in outdoor pools.

If too low (< 30 ppm): Add Cyanuric Acid.
If too high (> 50 ppm): Dilute the pool water by partially draining and refilling.

Most pool stabilisers are available from Mitre 10 or your local pool store.

Step 6: Control Calcium Hardness

Calcium Hardness is important for protecting your pool’s surface and preventing scaling.

If too low (< 180 ppm): Add Calcium Chloride (Calcium Hardness Increaser).
If too high (> 400 ppm): Partially drain and refill the pool, or use a calcium reducer.

For fibreglass pools, maintaining lower calcium hardness helps prevent roughness or staining.

Step 7: Shock the Pool When Needed

Every few weeks (or after heavy usage), shock the pool with a high dose of chlorine to eliminate bacteria, algae, and chloramines.

Use chlorine shock for routine maintenance.
Use non-chlorine shock if you want to swim shortly after treatment.

Pool shock treatments are available from Para Rubber and Bunnings NZ.

Step 8: Regularly Circulate and Filter the Water

Ensure your pool pump and filter are running efficiently. It’s recommended to:

Run the pump for at least 8 hours daily in summer (4-6 hours in winter).
Regularly clean or backwash the filter.

Check out The Pool Shop NZ for filters, pumps, and cleaning accessories.

Step 9: Prevent Algae with Algaecide

If you’re dealing with algae, or want to prevent growth, use an algaecide.

Use preventative algaecide weekly during summer.
Use stronger algaecide if you’re dealing with an algae outbreak.

Find effective algae treatments at Mitre 10 or local pool supply stores.

Step 10: Keep a Regular Maintenance Routine

Maintaining balanced pool water is easier if you stay on top of it!

Test the water at least twice a week during summer and weekly in winter.
Clean the pool regularly, including scrubbing walls and vacuuming debris.
Check chemical levels after heavy rain or a big swimming day.

For seasonal pool maintenance tips, visit SPASA New Zealand – the industry body for pool and spa owners.

Final Thoughts

Balancing pool water chemistry may seem complicated at first, but with regular testing and maintenance, it becomes second nature. By following these steps and using locally available products, you can enjoy a healthy and sparkling pool year-round.

Need expert advice? Visit your nearest New Zealand pool shop or check out online guides from SPASA NZ for more info. Happy swimming!

Pool Owners New Zealand