How to Close an Inground Pool for Winter – Step by Step

It is always a sad moment when the pool season ends meaning no more watery fun until the spring. In order to be able to get your pool ready as quickly as possible in the spring, and to reduce the possibility of damage, you need to make sure you close (winterize) your pool properly.

Ensuring the pool is as clean as possible is the best start to closing your pool for the season, followed by adding winterizing chemicals, lowering the water level, blowing out the pool lines and then coving the pool. It really isn’t as difficult as it may sound.

So without any further delay, let’s get started! 

how to close an inground pool
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Should you close a pool for the winter? 

If you live in an area where winters are very mild then you may not need to do much to your pool for the winter. For example, I now live in an area where winter temperatures never drop below 50ºF so I actually do very little except keep an eye on the chemicals and clean my pool less frequently.

But if the temperature where you live is likely to dip below freezing for any length of time during the winter then closing the pool is essential.

All the inground pool owners out there know the drill of all the chemicals, algae growth, and more. Suppose you leave your pool unattended or close your inground pool in a sloppy way. You can be assured of being greeted with pretty nasty green pool water at the start of the next pool season if you don’t take all the necessary measures to keep your swimming pool fresh. 

Apart from the obvious gross condition of your pool water that makes it unfit for the swim season, the unbalanced water chemistry due to the lack of chemicals, dirt, and more will also affect the circulation system of your inground pool, especially the skimmer line. 

Winterizing your inground pool will ensure that both your time and money are saved when you pull out the covers for the pool season. Also, removing the water from the pool through the pool pump helps you ensure that there is no extra damage done when the water freezes.

You can even use a winter cover to prevent any accidents. Further helping your pool maintenance are the chemicals that you add to balance the water chemistry. 

When should you winterize a pool? 

This is hands down the most vital factor to consider as it will greatly affect the closing of your pool as well, as this varies depending on the weather in your area.

Typically, if the temperature of your area stays below 65°F (18°C) during the offseason, then it is better to wait until the temperature falls below that point to close your pool. The low temperature will help make sure you have a clean pool as algae don’t like the cold weather, allowing your pool to have low algae growth. 

Leaving your pool open during this period will also make the whole process of closing a piece of cake as it will be easier to clean, test, and balance the water. 

However, if your winter feels like a warm July day with a temperature above 18°C, then you don’t need to do the whole ritualistic cleaning and balancing of the inground pool. All you need to do is keep your pool pump hooked up and run it daily throughout winter (as I do).

Also, you have to keep up with your pool maintenance until the pool season, although you generally will not need to do this as often as during the swimming season. Just make sure you test the water quality weekly and adjust with chemicals as necessary.

losing inground pool for winter

What equipment do I need for closing my inground pool? 

There are some necessary items of pool equipment and chemicals that you might need to close your pool.

Here is a list of equipment and chemicals that you may need to close your pool and for pool maintenance during the off-season: 

Winterizing Chemicals Equipment
Chlorine
Winter Pill
pH increaser
pH decreaser
Sanitization product
Cyanuric acid
Pool antifreeze
Pool Enzymes
Alkalinity increaser
Calcium hardness increaser
Algaecide
Off-season solid pool cover
Pool brush
Pool vacuum or Automatic cleaner
Skimmer drain plugs
Pool cover
Shop-vac or air compressor
Tools for removing pool accessories- eg: ladders
Winter pool cover pump
Winter pool plugs for return jets
Pool test strips
Metal sequestrant
closing inground pool

Pool closing tip

Although closing your pool is not rocket science, as you will see in the step-by-step guide below, many people are very nervous about doing it themselves. So if you are still not confident enough to do it yourself then you can pay a pool company to do it for you BUT make sure you are at home when they do it.

Follow them around and watch exactly what they do, making notes or even videoing, so that next year you will know enough to do it yourself.

Instead, you could check out the course below for much less than the cost of a company closing the pool.

Pool Winterization Video Course

Save over $300 a year by closing and winterizing your pool yourself using Swim University’s step-by-step video course. It covers closing both inground and above ground pools.

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Use the discount code EASY10 at checkout to save 10% on this Swim University course.

How to Close an Inground Pool for Winter - Step by Step 1

9 steps: closing an inground pool for winter

Okay, now that you are all geared up, it is time to do the real work. We won’t pretend that it is a cakewalk to close your inground pool, but if you want a clean pool in spring rather than a swamp you need to make it as clean as possible.

But what do you need to do to close your in-ground pool? 

Well, to help you out, I have compiled this handy guide that will walk you through all the steps you need to take so that you close the in-ground pools efficiently.

Step 1: Get ready to do some serious cleaning 

Before you get to balancing water chemistry and doing all the complicated steps, you need to start with cleaning the pool. First, scrub the pool walls and get into all the corners and cracks to get rid of all the accumulated dirt. You should then give the pool a thorough vacuuming to clean any residue on the bottom of your pool. 

Use a brush to thoroughly scrub any algae growth or any cracks that could potentially serve as a place for algae to hide and grow. The cleaner the pool is before closing it the better it will be in the spring when you open it.

Doing this also helps to make your pool ready for all the winter pool chemicals you will be adding further into the process. 

Step 2: Put your pool water to the test 

how to close your inground pool for winter

You might be tempted to skip this step because you are closing the pool. Do you need to test the water, especially when you will add more pool chemicals to it after? The simple answer to that is yes. You do need to test the water chemistry of your above-ground pool with a pool test kit, or you can even go to the local water authority for more precise readings.

Either way, you have to note the chemical concentrations like pH, alkalinity level, etc are balanced so that the water of your inground pool does go musky or cloudy while it’s closed.

When you test condition of the pool’s water, you must further check that the chlorine level is no more than 5 PPM. Excess chlorine concentration can take over the other chemical additives you might add to the pool’s water. 

Step 3: Add winterize pool chemicals

After you are done balancing the chemicals, add some winterizing pool chemicals that will prevent your pool from turning into a mess of algae, dirt, leaves, etc., over the winter months.

Furthermore, there are various winterizing chemicals out there, but to determine the chemicals your pool requires, it is recommended you inspect your inground pool thoroughly to spot all the problems that need fixing. 

If there are signs of algae growth in your inground pool or any mesh panel that can give space for dirt, insects, or vegetation to enter your pool, then you should add some algaecide in your pool. You can do a double dose of this chemical if your pool is prone to algae.

However, you must be careful with the amount of this chemical you use in your pool as it contains copper, which increases the concentration of metal elements in pool water. 

In order to prevent elevated metal content in the pool water, you can use a metal sequestrant as it saves the pool from awful metal stains. Moreover, it helps stop the metal from settling and oxidizing, giving you a clean swimming pool.

It is important to use algaecide properly, as it is not the only metal source; your in-ground pool’s water can also get these from its water source or another cleansing substance. 

You can even add pool enzymes to help the algaecide disintegrate your pool’s organic contaminants. Also, to keep your pool clean and balanced throughout the winter, you can use Winterpills, which is a combination of chlorine and a clarifier that you can add before closing the pool.

Even after taking all the necessary precautions, one problem you can face is the freezing of pipes which is common if you live in a place with frigid winters. But worry not, we have got you here as well. Swimming pool antifreeze will ensure that the pipes or the water are not frozen as it can lead to accidents too. 

Pool winterizing chemical kit

You can either buy a complete chemicals kit such as the Pool Winterizing and Closing Chemical Kit

In The Swim Pool Winterizing and Closing Chemical Kit - Up to 35,000 Gallons

Or you can buy what is known as a winter pill such as the SeaKlear AquaPill AP71 WinterPill

AquaPill WinterPill Pool Winterizer Pill, Large, up to 30,000 Gallons by SeaKlear

Step 4: Shock your pool

Before closing and covering the pool for the winter, you should add some shock to your pool which helps in making your pool balanced and ready to be closed for the off-season.

If using liquid pool shock you can pour it into the pool and let the circulation system mix it around.

If using granular shock you should mix this in a bucket of pool water first. Do not add it straight to the pool.

It may be best to do this and leave the pump running overnight before proceeding to the next stop of lowering the water level.

Step 5: Just one more round of cleaning

The last thing you want is to uncover your pool in the spring and find the pool filters full of debris. So, the best way of avoiding that is to ensure the pool is as clean as possible before you close it.

Once you have vacuumed the pool make sure that you properly backwash the filter system (if it is a sand filter or a DE filter) so that is as clean as it can be too. Read How to backwash a sand filter if you are unsure how to do this.

If you have cartridge filters then remove, clean and replace the cartridge, and you are good to go. See How to clean pool cartridge filters if you are unsure how to do this.

Step 6: Lower the pool’s water level 

The primary purpose of doing this is to prevent damage to the pool plumbing due to freezing water or snow. 

You can lower the water level below the skimmer opening using the pool pump, drawing water from the main drain only, with the multiport valve on the waste setting or by using a submersible pump.

For full instructions, read my full post How to drain an inground pool below skimmer.

Step 7. Prepare the filter and pump

Remove all drain plugs on the pool pump and the filter housing and allow the water to run out. Put the drain plugs in a safe place so you don’t lose them in the spring.

Set the multiport valve lever to the winter setting if it has one.

Step 8: Drain the heater (if you have one)

If you have a pool heater you will need to locate all the drain plugs and allow all of the water to drain. Then replace the plugs or close the valve.

Step 9: Blow out the pool lines

This step is essential, especially if you live in a cold part of the country. Blowing out the return lines calls for you to remove/drain water from the lines and the pump which lets you avoid any frost damage to the pool equipment or skimmer. 

You will need an air compressor, air blower or shop vac to push air through the system and expel all of the water in the lines.

You will need to uncouple the return line and insert the blower. This is then run until no more water comes out of the return jet. Then you need to plug the return jets using suitable drain plugs.

Then you uncouple the input line and blow out the lines and do the same until no more water comes out of the skimmer/s which then also need to be plugged.

After that, you will need to pour pool antifreeze into the lines before reconnecting them. 

Step 10: Remove pool accessories

You are almost done with closing out the pool for the winter. All you need to do is remove all pool accessories before you get the inground pool completely covered. This prevents them from being damaged and even gives you the chance to clean the pool equipment before the spring. 

Go ahead and remove the other pool equipment including automatic cleaners, skimmer baskets, ladders, etc., from the pool before closing it. Furthermore, this is also a great time for you to remove your saltwater chlorine generator if you have a saltwater pool. 

Step 11: Swimming pool cover up 

closing an inground pool for winter
Solid winter covers are expensive but convenient

You are nearly finished as it is time to get out your winter cover to cover your pool and leave it until the start of the pool season. This will keep your pool safe from snow, dirt, leaves, insects, and more. 

Also, you can choose from an automatic pool cover, a removable winter cover, a solid cover or a mesh safety cover. You must choose the one that is best suited for you as the winter pool cover keeps the contamination away and the water chemistry well balanced.

Personally, I wouldn’t go for a mesh cover as when it rains the pool will become full again.

Related articles

If you have an above ground pool – How to winterize an above ground pool

How to open an inground pool