For pool owners in Canada, proper winterization is not just a recommendation—it's a necessity. As temperatures drop below freezing for extended periods, an improperly closed pool can suffer severe and costly damage. This comprehensive guide will walk you through the pool winterization process step-by-step, helping you protect your investment through the harsh Canadian winter.

When to Close Your Pool

Timing is important when it comes to pool closing. In most parts of Canada, the ideal time to close your pool is when the water temperature consistently stays below 15°C (60°F). This typically occurs in late September to mid-October, depending on your specific location.

Closing too early when temperatures are still warm can lead to algae growth under your cover. Closing too late risks freezing damage to your equipment and plumbing.

Essential Supplies for Winterization

Before starting the winterization process, gather these supplies:

  • Pool water testing kit
  • Winter chemical kit (including algaecide, shock, and winter enzyme treatment)
  • Pool antifreeze (non-toxic, pool-grade only)
  • Expansion plugs for return lines
  • Rubber winterizing plugs for skimmers
  • Air compressor or shop vac
  • Winter pool cover
  • Cover pump (if using a solid winter cover)
  • Cover anchors or water bags
  • Pool closing tool

Step-by-Step Winterization Process

1. Clean the Pool Thoroughly

A clean pool is essential for successful winterization:

  • Skim the surface to remove leaves and debris
  • Brush the walls and floor thoroughly
  • Vacuum the entire pool
  • Clean the waterline with tile cleaner
  • Remove all ladders, rails, and other accessories
  • Clean and store all removed items

Any dirt or algae left in the pool will be much worse by spring, so be thorough with this step.

2. Balance the Water Chemistry

Properly balanced water protects your pool surfaces throughout winter:

  • Test and adjust pH to 7.2-7.6
  • Adjust alkalinity to 80-120 ppm
  • Ensure calcium hardness is 175-225 ppm for vinyl pools or 200-275 ppm for concrete/plaster pools

Balancing your water chemistry prevents scale formation and surface damage during the closed season.

3. Add Winterizing Chemicals

Winter chemicals help prevent algae growth and protect your pool:

  1. Shock the pool with a chlorine shock treatment at double the normal dose
  2. Run the filter for at least 8 hours after shocking
  3. Add winter algaecide according to package directions
  4. Add winter enzyme treatment to help break down organic contaminants
  5. Run the pump for 1-2 hours to circulate these chemicals

Never mix chemicals together directly. Add each one separately and allow circulation between additions.

4. Lower the Water Level

For areas with freezing winters like Canada, the water level must be lowered:

  • For mesh safety covers: Lower water 30-45 cm (12-18 inches) below the skimmer
  • For solid winter covers: Lower water 10-15 cm (4-6 inches) below the skimmer

The exact level depends on your specific pool type and cover. Don't drain the pool completely, as water provides necessary counterbalance pressure against groundwater.

5. Drain and Winterize the Equipment

Protecting your equipment from freezing is crucial:

Plumbing Lines

Water expands when it freezes, which can crack pipes and fittings:

  1. Turn off all power to pool equipment at the breaker
  2. Remove drain plugs from the pump, filter, heater, and chlorinator
  3. Use an air compressor or shop vac to blow out the lines:
    • Attach the air source to the pump drain port
    • Blow air through the system until no more water comes out of the return lines
    • Insert expansion plugs into the return line fittings once clear
  4. Insert winterizing plugs in the skimmers
  5. Pour pool-grade antifreeze into the skimmer and pump basket (never use automotive antifreeze)

Filter Equipment

Different types of filters require specific winterization:

  • Sand Filters: Backwash thoroughly, remove drain plug, set multiport valve to "winterize" position (or between settings if no winterize position exists)
  • Cartridge Filters: Remove cartridges, clean thoroughly with cartridge cleaner, allow to dry, and store indoors
  • DE Filters: Backwash, remove drain plug, remove and clean grids, reassemble without DE powder

Pumps and Heaters

  • Remove all drain plugs
  • Store drain plugs in the pump basket for easy location in spring
  • Cover equipment with weatherproof covers if stored outdoors
  • For gas heaters, shut off the gas supply and follow manufacturer's specific winterizing instructions

6. Install the Winter Cover

A quality winter cover protects your pool from debris and sunlight:

  1. Clean the pool deck area thoroughly
  2. Remove any sharp objects that could damage the cover
  3. Place the cover over the pool, ensuring it's centered and even
  4. Secure the cover according to its type:
    • Safety covers: Tighten anchors evenly using the installation tool
    • Solid covers: Secure with water bags or cover blocks (never use bricks or sharp objects)
  5. For solid covers, place a cover pump in the center to remove rainwater and melting snow

Ensure the cover is tight with no sagging areas where water can pool.

Throughout the Winter

Periodic winter maintenance is still necessary:

  • Remove water, snow, and debris from solid covers regularly
  • Check the cover tension and securing mechanisms after storms
  • Monitor for any tears or damage to the cover
  • Ensure the cover pump is functioning properly

Special Considerations for Canadian Climate

Canada's extreme winter temperatures require extra precautions:

  • Use extra antifreeze in plumbing lines in areas with extreme cold
  • Consider removing and storing pumps and heaters indoors when possible
  • Use higher quality winter covers rated for snow load
  • Install a winter cover seal around the perimeter in areas with heavy snowfall
  • Consider an air pillow under solid covers to accommodate ice expansion

Common Winterization Mistakes to Avoid

Watch out for these common errors:

  • Not blowing out lines completely
  • Using automotive antifreeze instead of pool antifreeze
  • Closing the pool too early or too late
  • Not balancing chemistry before closing
  • Leaving water in pumps, filters, heaters, or chlorinators
  • Improperly securing the winter cover
  • Not checking the pool periodically throughout winter

When to Consider Professional Closing Services

While many pool owners handle winterization themselves, professional closing services are worth considering if:

  • You're uncomfortable working with pool equipment
  • Your pool has complex systems (advanced heating, automation, etc.)
  • You have limited time or physical limitations
  • You have a high-end pool with expensive finishes
  • You want peace of mind knowing your pool is properly protected

A professional closing service from Viola Speri Pool Services includes all the steps above, performed by trained technicians with specialized equipment.

Conclusion

Proper winterization is essential for protecting your pool investment through Canada's harsh winters. By following this comprehensive guide, you can ensure your pool remains in excellent condition and minimize the work needed for spring opening.

At Viola Speri Pool Services, we offer professional pool closing services throughout Canada. Our experienced technicians can winterize your pool correctly, giving you peace of mind all winter long. Contact us today to schedule your pool closing appointment or learn more about our pool maintenance services.