When Should You Close Your Pool in Mississauga? A Guide for Fall 2025

As summer winds down and the cooler air starts to roll into Mississauga, many pool owners begin asking the same question: When is the right time to close my pool for the season? Closing your pool too early can lead to unnecessary algae growth, while waiting too long risks damage from freezing temperatures.

In this guide, we’ll walk you through the ideal timing, key factors to consider, and professional tips for closing your pool properly in fall 2025.

Why Timing Matters

Closing your pool isn’t just about convenience—it’s about protecting your investment. Doing it at the right time helps:

• Prevent algae growth

• Maintain water balance

• Protect plumbing and equipment from freezing

• Reduce spring cleanup and costs

Mississauga’s weather can vary year to year, but fall typically brings cooler nights starting in late September, with the first frost often hitting by mid-to-late October.

Ideal Time to Close Your Pool in Mississauga

For most pool owners in Mississauga, the best time to close your pool is between late September and mid-October, depending on weather conditions and how much you still plan to use your pool.

Look for these key signs it’s time to close:

• Water temperature consistently drops below 15°C (59°F)

• Air temperatures are regularly below 10°C at night

• You’ve stopped using the pool regularly

• Falling leaves are increasing debris in the water

Pro tip: Closing your pool when water temperatures are cooler helps prevent algae from growing under the winter cover.

Don’t Close Too Early

It might be tempting to close the pool right after Labour Day, but closing too early—while the water is still warm—can backfire. Algae thrives in warmer water and can bloom under the cover if your chemicals aren't perfectly balanced.

Waiting until the water is consistently cool helps your pool stay cleaner over the winter, making your spring opening much easier.

Step-by-Step Fall Pool Closing Tips

Once you're ready to close your pool, here’s a general checklist to follow:

1. Clean the Pool Thoroughly

   • Skim, vacuum, and brush the walls and floor

2. Balance Your Water Chemistry

   • Ensure pH, alkalinity, and calcium hardness are within ideal ranges

3. Shock the Pool

   • Use a chlorine or non-chlorine shock to eliminate contaminants

4. Add Winterizing Chemicals

   • Algaecide and stain prevention treatments help protect during the off-season

5. Lower the Water Level

   • Lower below the skimmer and returns if using a solid cover

6. Drain and Store Equipment

   • Remove ladders, hoses, solar covers, and store them clean and dry

7. Blow Out the Lines and Plug the Returns

   • Essential for preventing freeze damage in plumbing lines

8. Install a Winter Cover or Safety Cover

   • A secure cover keeps out debris and helps maintain chemical balance

Let the Pros Handle It

If you’re unsure about the closing process—or just want peace of mind—our experienced team at Pallett Pool and Spa offers professional pool closings in Mississauga and the surrounding area. We’ll make sure everything is done right, so you can relax through the winter knowing your pool is protected.

Book Early—Avoid the Fall Rush

September and October are our busiest months for pool closings. Booking your pool closing early ensures you get your preferred date and helps avoid delays due to weather or schedule changes.