Top 5 Chemical Balancing Tips Before You Close Your Pool

As the end of summer nears in Mississauga, it's time to start preparing your pool for closing season. One of the most critical steps you can take before covering your pool for the winter is proper chemical balancing. When your water chemistry is dialed in, it helps protect your pool liner, equipment, and surfaces from damage — and makes for a much easier opening next spring.

Here are the top 5 chemical balancing tips to follow before you close your pool for the season.

1. Test and Balance Your Water 3–7 Days Before Closing

Don't wait until closing day to check your pool's chemistry. Testing the water a few days in advance gives you time to correct any imbalances.

Key levels to check:

• pH: 7.2 – 7.6

• Alkalinity: 80 – 120 ppm

• Calcium Hardness: 200 – 400 ppm

• Chlorine (or sanitizer level): 1 – 3 ppm

• Cyanuric Acid (stabilizer): 30 – 50 ppm

Make small adjustments as needed to avoid over-correcting. A well-balanced pool is less likely to develop scale, corrosion, or algae under the winter cover.

2. Shock the Pool Before Closing

Once your pH and alkalinity are in the right range, it’s time to shock the pool. Shocking eliminates contaminants, organic waste, and bacteria that may be lurking in the water.

Tips:

• Use a chlorine shock if you normally sanitize with chlorine

• Shock 1–2 days before covering the pool

• Run your pump for at least 8–12 hours afterward

This gives the chlorine time to circulate and oxidize waste, ensuring your pool is as clean as possible before going dormant.

3. Add a Quality Algaecide

Even if you’ve never had an algae problem, adding a winterizing algaecide is a smart final step before closing. Cold water slows algae growth, but it doesn't stop it completely — especially if temperatures fluctuate in early fall or spring.

Choose a non-copper, long-lasting algaecide designed for winter use. Add it after shocking and just before you lower the water level and install the cover.

4. Adjust Calcium Hardness to Prevent Scaling

Mississauga’s water can vary in hardness, and if calcium levels are too high or too low before closing, it can cause problems under the cover.

• Low calcium: Water becomes corrosive, potentially damaging your liner or surfaces

• High calcium: Water can become cloudy and lead to scale buildup

Keep levels in the 200–400 ppm range. If your pool tends to have hardness issues, consider adding a scale prevention treatment as well.

5. Don’t Forget the Phosphate Remover

Phosphates feed algae — and even with proper sanitation and algaecide, high phosphate levels can lead to problems during the off-season.

Before you close, test for phosphates and treat if needed. This extra step goes a long way in keeping your water crystal-clear until spring.

Final Tip: Keep the Water Circulating Until Closing Day

After you've added all your chemicals, make sure to keep the pump running for at least 24 hours to ensure even distribution. You want everything fully circulated before turning off the system and closing the pool.

Need Help Getting Your Pool Chemistry Right?

Balancing your pool before closing can feel overwhelming — but it doesn’t have to be. At Pallett Pool and Spa, we offer professional fall pool closings and water testing to help Mississauga pool owners wrap up the season the right way.

Stop by our store for free water testing, or book a closing service with our experienced team to take the hassle off your plate.

Book Early — Fall Closings Fill Up Fast!

Closing your pool with balanced water is the best way to protect your investment over the winter. Whether you're a seasoned pool owner or closing for the first time, start early and take the time to do it right.

Need help? Contact Pallett Pool and Spa today to schedule your pool closing or pick up everything you need to balance your water like a pro.