Common Mistakes to Avoid When Closing Your Pool

Closing your pool isn’t just about putting on a cover and calling it a day. Doing it wrong can lead to expensive damage, algae growth, and a lot of hassle when it’s time to open the pool again. Avoiding simple mistakes now will save time and money later.

What Happens if You Close Your Pool Incorrectly?

• Water can freeze and crack pipes or equipment

• Algae can bloom over the winter

• Pool surfaces may stain or erode

• You may face a longer, more expensive opening process in spring

Mistake #1: Not Balancing Your Pool Water

Some pool owners skip testing or think it doesn’t matter since the pool will be unused. But unbalanced water can cause serious problems.

Why It Matters

• Low pH can corrode metal and pool surfaces

• High alkalinity can create cloudy water and scaling

• Improper calcium hardness can damage plaster or liners

What to Do

• Test water pH, alkalinity, and calcium hardness

• Adjust each level to the recommended range before closing

Mistake #2: Not Cleaning the Pool Thoroughly

Leaving leaves, dirt, and debris in the water when closing up is a major mistake.

Problems It Can Cause

• Debris can cause staining over winter

• Organic matter leads to algae growth

• It makes spring cleaning much harder

What to Do

• Skim and vacuum the pool thoroughly

• Brush walls and floor

• Clean out skimmer baskets and pump basket

Mistake #3: Skipping the Final Shock Treatment

Some pool owners forget to shock the pool before adding the winter chemicals, or they skip it completely.

Why It's Important

• Shocking kills bacteria and algae spores

• Prevents growth during the off-season

What to Do

• Use a chlorine shock a few days before closing

• Let the pump run for 24 hours to circulate it

Mistake #4: Not Lowering the Water Level Correctly

Water level is key to protecting your pool and equipment.

Why It Matters

• Too high, and water may damage the cover or freeze inside skimmers

• Too low, and it may affect the liner or structure

What to Do

• Lower water below the skimmer for vinyl and concrete pools

• Follow manufacturer guidelines for fiberglass pools

Mistake #5: Not Blowing Out the Lines

Water left in pipes over the winter can freeze and burst the plumbing.

Why It's a Risk

• Frozen water expands and cracks pipes

• Can damage filters, pumps, and heaters

What to Do

• Use a shop vac or air compressor to blow out all plumbing lines

• Plug the lines after blowing them out

• Add pool-safe antifreeze if needed

Mistake #6: Forgetting to Drain Equipment

If you leave water in your pump, filter, or heater, they could crack in freezing temperatures.

What Needs Draining

• Pool pump

• Filter (remove and clean cartridge or backwash sand filter)

• Heater and chlorinator

What to Do

• Remove all drain plugs and store them in the pump basket

• Tilt equipment slightly to let all water out

Mistake #7: Using the Wrong Pool Cover

A cheap or incorrect pool cover can cause more problems than it prevents.

Cover Problems to Watch For

• Doesn't fit tightly and lets debris in

• Can't handle snow or rain load

• Tears easily or sinks into the water

What to Do

• Use a durable winter pool cover that fits securely

• Anchor it properly using water bags or cover clips

• Check it regularly for damage or sagging

Mistake #8: Ignoring Safety Measures

Closing your pool doesn’t mean safety rules go out the window. If children or pets are around, your closed pool should still be secure.

Safety Steps

• Use a safety cover if you have children or pets

• Install barriers or fences as needed

• Keep cover pumps working to prevent water buildup

Mistake #9: Not Labeling or Storing Pool Parts Properly

Come spring, you don’t want to be searching for random pieces or forget where they go.

What to Do

• Store all small parts in a labeled container

• Keep the pool manual nearby for reference

• Write notes about chemical levels and steps taken during closing

Mistake #10: Waiting Too Long to Close

Some pool owners think they can stretch the season longer by closing late. But that increases the chance of algae and damage.

Ideal Timing

• Close when water temperatures drop below 65°F (18°C)

• Closing too early can also be a problem if it’s still warm

Pro Tips to Make Closing Easier

• Create a pool closing checklist to stay organized

• Take photos of your setup to help during opening

• Ask a professional for help if you're unsure about any step

Avoiding these common mistakes ensures your pool stays in good condition during the off-season and makes the next opening process smooth and stress-free. Take your time, plan well, and your pool will be ready to enjoy again in no time.