Pool Care Pool Opening and Closing

How to Close an Inground Pool


Like all the festive holidays, the warm weather has to come to an end. Winter is around the corner, and we all have to get ready for the chilly weather. One thing that needs our attention is the lovely swimming pool that helped us enjoy the warm period to our fullest. You did enjoy having a warm, refreshing bath. Right? Well, at least I did!

I don’t know about you, but I’m hoping you did too. And now, if you want to get the same enjoyment next summer, you’ll want to close your inground pool right.

How to close an inground pool isn’t a challenging task if you do it right. All you will need is this post and your handy hands. But before you can get started, there are things you need to know about closing an inground pool.

Why Should You Close Your Inground Pool?

Maybe you heard from a friend or read that a swimming pool has to be closed, but you don’t understand why. You can jump to the next section if you do, but it’d be best to read it through. You might learn something new.

Closing your swimming pool in the winter is extremely crucial if you still use it next summer. It helps keep it swimmable, maintains the pool parts, equipment, and accessories, and best of all, it saves you money.

Can you imagine if you left the pool uncovered for a while during the summer? Maybe you left for a vacation for a week.

When you return you’ll probably have to deal with all kind of a mess, dead bugs, twigs, and other yucky debris that might have found their way it to the water.

But because you don’t leave it unattended, you maintain it a couple of times in a week; you avoid all the mess.

The same scenario could happen during the winter. You leave everything exposed to the cold weather. You don’t get time to skim the water, brush and vacuum the pool. All types of debris, including the falling leaves, end up in the pool.

Because of the extreme cold, the debris starts to rot and settle on the pool bottom, they clog the skimmer, and the pool water chemistry goes havoc. And the worse happens, your pool pipes bursts or crack because of the freezing water.

When the winter is done, and all the ice melts down, what you see can break your heart. You will have a lot of work in your place to make the swimming usable again.

The pipes will need repairs and replacements. The water chemistry will need a lot of chemicals to get them balanced again.

And don’t get me wrong, I’m not scaring you, this is something I have a witness with some swimming pool that their owners had to do a total renovation to revive it.

In short, you will need a lot of time and money to get things going again. And you could make all the hassle go away and make things simpler next summer if you close your inground pool the right way.

When is the Best Time to Close Your Inground Pool?

Winterizing your inground pool requires timing. You have to get it right, or else you might do it early and end up wasting your energy, or do it late and end up with an already damaged swimming pool.

The best time to close your inground pool should be when your area temperatures go below 65°F or 18°C. The lower temperatures help control pool algae as it tends to make the water inhospitable for them.

When you leave the pool open until the weather cools down, you have easy cleaning, testing, and balance during the closing time.

If you live in an area where that experiences warm days during the winter, something above 65°F (18°C), you might want to take the opportunity to check on your pool.

Use this time to test and balance your inground pool water chemistry throughout the winter season. It will help keep the water cleaner and clearer and make everything easy during the reopening.

What Do You Need to Close An Inground Pool?

Before you can start winterizing your inground pool, there some things you need to put together. They will make the whole process easy, straightforward, and seamless. They include:

  • Water chemistry test kit
  • Chlorine or your preferred sanitizer
  • Pool brush with Telescoping pole
  • Metal sequestrant
  • Winter pool cover
  • Air compressor
  • Rubber plugs
  • Pool vacuum
  • Algaecide
  • Pool Shock Treatment
  • Water tubes

You will also need tools ideal for removing pool accessories, and the following are optional depending on your water test results.

  • Calcium hardness increase
  • Alkalinity increase
  • pH decreased
  • pH increaser

Ensure you have everything before you can start closing your swimming pool. The list might seem long, but you might some already – make sure.

How to Close an Inground Pool (Step by Step)

Now that you’ve everything required for the whole inground pool winterization, we can begin. Here are the steps to follow.

Step 1: Brush off your pool surfaces

It’s best to start with what you can see. Before anything else, you’ve to clean the pool to make the next steps easier.

Pick your pool brush and attach it to a telescoping pole if it doesn’t have it. It will allow you to reach the pool walls, floors, nooks, and crannies with ease.

Brushing the surfaces will help you kick up all the sediments hanging around and disturb the algae spores.

Do not, at any circumstance, use cleaning chemical as it will contaminate your pool water forcing you to drain it and refill with fresh water.

Once you have scrubbed all the surfaces, you can take your pool vacuum and manually sack the dirt and debris out.

If you come across algae symptoms while brushing, make the cleaning thorough. It will help breakdown the algae for easy vacuuming.

It also helps in disturbing the algae blooms to make them more susceptible to the treatment chemicals you will be adding later.

Step 2: Test the Water

After all the surfaces are clean, test your pool water. You have options here; you can do it yourself with a water chemistry test kit or take a water sample to the nearest local pool store to get more accurate test results.

One thing you will need to balance at this stage is the chlorine levels which must be below 5-ppm (parts per million.

High chlorine levels could interfere with the strength of the other chemicals and additives you’re about to add.

Step 3. Add Winterizing Chemicals

One of the things that protect your pool during the winter period is the winterizing chemicals you have to add while balancing the water chemicals.

You don’t add all the winterizing chemicals depending on the place you live and the state of your swimming pool.

#a) Metal Sequestrant

Start by adding metal sequestrant if the test said your pool has high metal levels or if you use well water as your pool water source.

The additive suspends the metals in the water, preventing them from settling on your pool surfaces, oxidizing, and causing stains.

#b) Algaecide

Algae is a nasty pool contaminant that can infest your pool during the winter. Adding one dose of algaecide will help prevent algae spore growth during the closed period.

If the pool cover has a mesh panel or dirt and leaves can still get into your pool during this period, it’d be best to add a double dose.

#c) WinterPill

WaterPill, like chlorine tables and floaters, protects your pool during the whole season. Unlike the WaterPill, chlorine tablets and floaters might not dissolve or distribute during the winter.

WaterPill dissolves over several months and contains both clarifier and sanitizer. It will also distribute itself well, adding extra protection.

#d) Antifreeze

The last winterizing chemical is antifreeze. It helps protect the pipes from freezing during the winter period.

After blowing out the pipes, some water might remain there and prone to freezing. But with antifreeze, you don’t have to worry; it will prevent freezing.

Choose the antifreeze chemical depending on temperatures your pool gets during the winter, and make sure it’s pool antifreeze and not car antifreeze.

Step 4: Shock Your Pool

Shocking your pool is necessary to give your pool sanitizer extra strength to kill bacteria and algae spores.

It’s best to give your pool water one last shock a night or few days before you can close it. It’s not a difficult process; you can DIY it.

The most important thing to do is follow the correct procedure and manufacturer’s instructions and directions.

If you noticed some algae blooms while cleaning it, double or triple the Pool Shock Treatment, depending on your assessment of the algae problem severity.

The best time to do this is overnight, as, during the day, the sun might gobble the chlorine before it can work.

Another thing, it crucial you run the pool pump and the circulation system overnight to help with shock distribution to all the corners.

Do not forget to test the water the following day to ensure all the chemicals are at their optimal levels.

Step 5: Clean or Backwash Your Pool Pump and Filter

Now that everything is clean, it’s time to clean the cleaner. The last thing you want is to leave all the dirt, debris, and bacteria in the filter all winter.

You have to give your pool filtration system a thorough clean before closing it. Follow the right cleaning procedure for your pool filter type.

#a) Sand Filter

A sand filter is arguably the easiest to clean. All you need is to backwash it thoroughly by setting the multiport valve to a backwash position. You can add a cleaner made for sand filters to fasten the process.

Remember to set the multiport valve back to backwashing once you’re done. You will also need to drain it plus the pool pump and heater if you have one.

You can keep the plugs inside the pump skimmer basket for easy retrieval when reopening the swimming pool.

If the unit is too heavy to remove and store, you can find an ideal cover to protect it from the winter elements and make it waterproof.

#b) Cartridge Filter

Remove the cartridge filter, take out the filter cartridge, add cartridge filter cleaner or muriatic acid and clean the filter housing.

Apply the filter cartridge cleaner on the filter cartridge, rinse it with clean water and leave it to dry before taking it in for storage.

#c) Diatomaceous Earth (D.E.) Filter

With a D.E filter made to use D.E powder, you can use the same method you used with the sand filter. You can use D.E filter cleaner or backwash it. Drain all the water and store it right.

Note: Do not forget to clean the pool pump, drain it and store it appropriately.

Step 6. Lower the Water Level

If you live in a warm area with a dry climate and you’re closing your pool for reasons other than winterization, you can skip this step.

But if you need to winterize your pool, it’d be best to remove some water when closing it. It helps prevent freeze damage and also lowers the overflow degree.

It’s best to keep the water level below the tile border or at the skimmer bottom edge if you don’t use a tile liner.

If your area rains during the winter, check the water level to make sure it says under the tile liner or the skimmer bottom edge.

With the water inside the pool providing support to the pool cover, the water level should also be affected by the type of pool cover you use.

Remember, snow and debris will settle on the pool cover. It’d be best to read and follow the cover manufacturer’s recommendation.

But how do you lower the pool water level?

It’s quite simple; all you need pump the water out of the pool to waste until it reaches the ideal level. And since you just added the water chemically, direct the wastewater appropriately.

The best pace is into the nearest sanitary drainage sewage but checks with the local laws and regulations before doing so.

Step 7: Blow out the Pool Lines

After all the cleaning and balancing, you will need to take care of the water in the pool lines as it might freeze and cause damages.

However, if you live in those warmer areas where the temperature doesn’t get to freezing or below, you can skip the blowing step using antifreeze.

But if you love in the cold areas that freeze during the winter, it’s a must you remove every drop of water from the pool lines, pump, and filter.

Since you cannot achieve blowing the pool lines with your mouth, you will need an air compressor I mentioned in the list of items you will need.

But you have to be careful as the pool plumbings aren’t meant to withstand excess pressure. Purging them of water must be a delicate, gentle process.

The task is DIY capable, but I’d recommend hiring a professional for this step if you’re not certain you can do it. Any mistake could leave you with expensive repairs.

How do you blow pool lines?

Remove all the skimmer baskets, return fittings and drain plugs from the filter system. And as you can remember, the pump and filter are out.

The only thing you need to do now is attaching your air compressor (you can also use a shop vac) to the pump drain plug. If it’s not connecting directly, get an adapter.

Turn on the air compressor and slowly blow air into the pipe. Wait until the bubbles from the skimmer and return lines. If you’re using a ShopVac, suck out the water from the skimmer until it’s all dry.

Once all the water is out, insert rubber plugs in the holes in the skimmer bottom, return lines. If you live in a chilly area, use straight pressure plugs.

If you’re using a Salt Water system, remove it, including the chlorinator, drain them and store them. Flip the chlorinator circuit breaker and ensure the gas or power heater are also off.

Step 8: Remove the Pool Accessories

Leaving your pool accessories like ladders, rails, or steps installed during the winter can problems. The prolonged chemical exposure can damage their finishes or, even worse, cause rusting. The rusting will contaminate your swimming pool, and you will have another issue to deal with when opening it.

They might also prevent the cover from covering your pool completely, which is necessary to keep the intruders at bay. Removing the accessories allows the cover to completely protect the pool from everything, including debris, animals, bugs, and more.

Use the right tool to remove the accessories. Once they are out, clean them thoroughly and make sure they are totally dry before storing them. Pick an ideal storage place away from direct sunlight to prevent weather damage.

Step 9: Install your Winter Cover

You’re in the last stage now, installing the pool cover. There are two options; using a regular winter pool cover or using a safety pool cover. Your option is determined primarily by the region you live in and your budget.

Winter Pool Cover: it’s a comprehensive pool cover designed to protect pool water from contaminants and keep the water chemistry balanced. It does also prevent gaps along the pool edges, keeping it fully closed.

It needs a water tube or covers weights to prevent it from sinking. You will also need to drain water from the cover during the water to protect it from the heavyweight. You’ll also be protecting animals or people that might get trapped in the pooled water.

Clean and clear it from time to time using non-sharp objects like a soft brush. Removing the debris will give you an easy time when reopening.

Pool Safety Cover: it’s more expensive than a regular winter cover. It’s a better option to protect the pool from elements and prevent people or animals from falling into the pool water.

Some come in mesh design, while others are hybrid versions with a pane to allow the water to drain inside.

Using a hybrid safety cover, remember to lower the pool water level time and again during the winter as rain and melting snow will raise it.


And you’re done! That’s how to close an inground pool. As you can see, the steps are DIY. There may be one or two instances where I recommended you get a pro, but the rest is mostly DIY. If the process seems too long for you to follow, don’t shy to hire a professional. Yes, you might spend a lot of money, but you could be saving yourself some precious time.


About the author

Sharif Miah

Hi! I'm Sharif, the founder of Globo Pool® and I have been working in the pool & hot tub industry for the last few years. I love to share my experiences with people & hope you are enjoying my information and lessons!

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