Winterization of pool: How to Winterize a Pool

10 Steps to Winterize Your Inground Pool

When the long summer days come to a close, it’s time to think about how and when to winterize your inground pool. Some people don’t need to winterize their pool — we’re looking at you, sunbelt region! — but if you live in a colder climate, it’s a good idea to let your pool hibernate.

As with everything pool related, there is a specific process for winterizing your pool. It’s an easy process to follow, but

Winter pool closing steps must be done in a very specific order to ensure an easy pool opening the following spring. Follow the guidelines below to close your own swimming pool this winter!

1. Remove Ladders and Accessories

Loosen the ladder anchor socket bolt. When it rises about 1/2 inch, knock it down with a heavy wrench. Wiggle the ladder loose so the pool cover will fit properly. Inspect your ladder treads closely for cracks, and tighten any loose ladder bolts. Most ladders can be stored outside, but plastic steps may do better if stored inside. Also remove any handrails, fill spouts, eyeball fittings, pool cleaners and skimmer baskets. Store in a safe place where you can easily find them again in the spring.

2. Balance Water Chemistry

It’s important to start winterizing with balanced pool water chemistry. Test and balance the water chemistry, and adjust any chemicals if necessary. Balance water chemistry a few days before closing your pool to allow the chemicals time to disperse. Adhere to the following ranges for balancing water chemicals:

  • pH: 7.4–7.6 ppm
  • Total Alkalinity: 80–120 ppm
  • Calcium Hardness: 200–400 ppm
  • Chlorine: 2.0–4.0 ppm

Brush and shock your pool to remove any algae or other organic materials before closing your pool.

3. Clean the Pool

Skim, vacuum and brush the pool thoroughly, in that order. The pool should be spotless when you cover it. Remove every bit of organic matter possible, and give the pool one final skim (if necessary) before covering it for the winter. The cleaner the pool is when you close it, the better it will look next spring. Any debris or algae left in the pool during closing will dilute the strength of the winterizing pool chemicals.

4. Lower the Water Level

Lower the water level of your inground pool between 6-12″ below the bottom of the tiles, if you have a pool safety cover. For solid covers, only lower the water a few inches below the skimmer. Never lower the water level more than 18″, doing so can increase stress on your safety cover and cause the cover to rip or pull the anchors out of your deck.

If you are using a solid winter pool cover, lower the water level 3–4″ below the bottom of the skimmer opening, unless you’re using a skimmer plug. Skimmer plugs seal off the opening of your skimmer and keeps water out.

5. Turn off System Components

Turn off the pilot, shut off the gas supply, and turn the gas valve to OFF, on your pool heater. For gas heaters with pressure switches hanging down connected to a siphon loop, disconnect the pressure switch to drain the copper tubing. Open the drain plugs on both intake and outlet headers, making sure your heater is free of pool water.

Shut off power to the pump, light and heater at the circuit breaker box. If you have a timer clock for your pool pump, turn it off and remove the timer dogs. Disconnect power to any other electrical components that you don’t want to operate during the winter, such as a salt system or chemical pump.

6. Add Winter Closing Kit Chemicals

For this step, we highly recommend using a chlorine-free pool closing kit. These kits come with everything you need, and are packaged according to the size of your pool. They include chlorine-free pool shock, a strong winter algaecide, a stain and scale preventer, a slow-release floater with oxidizing chemicals. Shocking the pool just before adding algaecide can be a problem, as high chlorine levels break apart the polymer chains in algaecide and render it useless.

If you are not using a winter closing kit, be careful when using chlorine floaters. They can sink, tip over, or get stuck next to a wall, which will stain a pool’s vinyl or plaster surfaces during the winter. Use a high quality winter algaecide, a stain and scale preventer (chelator or sequestering agent) and some form of oxidizer to winterize your pool. Also, be sure to use non-chlorine shock, or only use chlorine shock 5-7 days before closing, to protect your winter algaecide.

If you have a mesh safety cover, we recommend using a pool enzyme product to help control algae growth during the winter. Also helpful is to check the water chemistry during mid spring, about a month before opening, and add another quart of algaecide or refill the floating chemical dispenser.

7. Drain Pump and Filter

DE filters should be opened up, and the filter grids should be hosed clean and inspected for rips or tears (mild staining is usually OK). Cartridge filters should have the cartridge removed and cleaned thoroughly. In both cases, after cleaning, reinstall the filter media back into the tank for winter storage. Lubricate any filter o-rings you come across in the process.

Adding antifreeze to your pump can damage the pump seal, so this should be avoided at all costs. It’s much better to completely drain all the water from the pump and filter system, including the chlorinator and heater, or any other pool equipment containing water.

After blowing the lines, place your grid assembly or filter cartridge back in the tank for safekeeping during the winter. Secure the filter lid and clamp band securely before and after blowing lines. Loose filter clamp bands can cause the filter lid to blow off during start-up, with hazardous results.

8. Blow out Water Lines

The best way to avoid pool freeze damage is to “blow out the lines” when you winterize your inground pool. Use a small air compressor at low psi or a high volume blower, like a Cyclone vacuum/blower or a powerful shop vac. Blow air through all equipment and pipes, both to and from the pool, and use pool plugs to prevent water from flowing back into the return lines. You’ll also want to install a skimmer guard to absorb the pressure of expanding ice and keep your skimmer from cracking. If you want to add non-toxic pool antifreeze to the lines for added peace of mind, now is the time to do it.

9. Fill Water Bags or Lift Safety Cover Anchors

Safety covers will have a series of anchors around the pool, which are recessed flush against the pool deck while the pool is in use. Use an anchor hex key tool to twist the anchors and bring them up to the surface.

If you are using a solid winter pool cover that requires water bags to hold it in place on the pool deck, fill the water bags where they will lay. If filled elsewhere, be careful not to drag or drop the water bags as they are moved around the pool. Fill bags only 80% full to allow expansion as the water freezes. Keeping several small pails or pans of water around the pool is a good idea to keep birds and critters from poking holes in the pool water bags for a drink. If you want something a little more durable than thin water tubes, you can also try using a product like Aqua Bloks, which will hold up to many years of use.

Above ground pools should use an Air Pillow, also called a pool pillow or an ice equalizer pillow, to absorb the expansion of the ice and prevent the ice sheet on the surface from putting pressure on the pool walls. Only inflate the air pillows roughly 60%–80%, so you don’t burst them.

10. Cover the Pool

Skim the pool again if needed, so the pool is as clean as possible. Clean off the pool cover too, to avoid bringing dirt and debris into your freshly cleaned pool. As you spread the cover over the pool, inspect closely for tears or rips. If possible, move these problem areas to the deck or close to the edge, and don’t place your cover pump over the tears. Apply cover patches as needed — there are poly patches for solid winter covers, and mesh or solid patches for safety covers. Secure the cover with water bags (inground winter cover), straps and anchors (safety cover) or a cable-&-winch assembly (above ground winter cover), depending on the type of pool cover you’re using.

That’s all there is to it! Follow these steps, and you will winterize your inground pool in no time. Once it’s closed, keep your pool cover as clean and dry as possible, and adjust as needed to keep it secure. Remember that solid pool covers with water bags are not safety pool covers, and can be dangerous for kids or adults who accidentally fall on top of them. Restrict access to the pool area during the winter, and keep an eye on the kids!

What to Expect: The Difference between Closing a Pool and Winterizing

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Well, the splashing is over for a while… Reason?


Time for the cocktails and cookouts to move inside.

During the fall it’s common in many parts of the country to say goodbye to pool season and prepare to close your inground pool for the winter months. In this next part of our What to Expect guide, I’ll try and dispel some of the myths and offer some helpful tips related to an inground pool closing and most importantly, winterizing.

The biggest thing that an existing or a new Latham pool owner must realize is there’s a huge difference between closing a pool and winterizing a pool. These terms are often used interchangeably, however, they two are very different procedures! Here in the Northeast, where this blog is centered, we not only close our pools but we winterize our pools.

Let’s take a closer look.

What is Closing a Pool?

When you close a pool you simply flip the switch and put the cover on. It’s possible that you could close your pool for a night, or while you’re away for vacation. Some homeowners close their pool to save on electricity costs or close an automatic safety cover to reduce costs related to pool maintenance.  Closing your pool means that your pool is not currently being used, but could be used again soon.

When you close your pool you’re most likely not that concerned about freezing temperatures or about water staying behind in your lines or vessels (for example: pump, filter, heater, chlorinator, etc.). In many parts of the southern United States homeowners simply close their pools during the cooler months. You can even set a pool to run an hour or two a day while the cover is in place.

What is Winterizing a Pool?

Different from closing a pool, winterizing your pool is the finale to the pool season. This means that your pool will not be used for several months, equipment is turned off, accessories are removed and the water is removed from lines and vessels.

In New England we not only close our pools but also we winterize our pools. This is a very important distinction to make because water can be destructive if left behind in a pipe or a pump housing when temperatures drop below freezing. Let’s remember that water expands 9-10% in volume once frozen (ouch!). This expansion is enough to fracture plastic, metal, or whatever vessel the water was left in. Because of the danger of not draining your pipes and equipment, the star performer of the winterization process is the air blower, commonly known as a liner vac. This is the tool that your pool professional will use to close your pool for the winter. The air blower that’s used for proper winterization absolutely must be a high volume and low pressure blower in order to effectively remove any and all water from pool pipes. I caution anyone in using a gas or electric tank type compressor because the high pressure and low volume that they produce could blow over the water in your pool’s pipes, leaving residual water and perhaps causing a big headache in the spring. Remember, 9-10%!

Winter Covers

The other main difference between closing a pool and winterizing a pool involves the type of cover that you use. In areas where temperatures drop below freezing and it snows, the preferred covers are solid or mesh safety covers. In most cases, I prefer a mesh cover for the winter because they allow water to pass through and chlorine gas to escape until the snow and ice comes to make it solid! These covers are made to withstand heavy snow and high winds and are secured with deck anchors as the last step in winterizing your pool.

Interested in learning more about winterizing your inground pool?
Watch pool professionals winterize a pool in our Proper Pool Winterizing Techniques video:

**Please note that in order to find the best winterizing treatment, contact your local Latham Independent Builder.


Important Things to Remember

  • Closing your pool and winterizing your pool are two very different things. To close a pool you could do as little as simply removing your ladder and put on a cover. To winterize a pool, and ensure that pool equipment will not be damaged in freezing temperatures, there is much more to do.
  • The water level in your pool will need to be lowered to approximately 1” beneath the skimmer and the pool water properly balanced 24 hours in advance of your pool professional’s arrival. Despite what some first time pool owners may think, water does stay in your pool throughout the winter months and must be balanced before saying goodbye.
  • Always blow out the pool lines from the skimmer back to the equipment.
  • Store your pool equipment neat and secure during the winter months. Make sure to remove your ladders and railings, as well as the ladder bumpers. Don’t forget to replace the ladder bumpers securely after draining excess water from the ladder’s side rails.
  • Be sure to check with your pool professional about any attempts at a DIY pool winterization as that may have an impact on your dealer’s and manufacturer’s warranties.

Other Articles in This Series:

  •  What to Expect When Building a Pool: Pre-Installation Preparation

Meet Our Expert

Mike Giovanone has installed over 12,000 inground pools during his 48 year career. He founded Concord Pools and Spas, one of North America’s most decorated and well-respected pool companies. Mike currently serves as Advisory Chairman for Concord along with being a special consultant to Latham Pool Products. Mike loves spending time with his wife Debbie along with his five grandchildren teaching them to swim, wakeboard and ski. He also is a dedicated board member of The National Center For Missing And Exploited Children (NCMEC).

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Winterizing your outdoor pool (Wintering)

A list of steps to take when preparing your outdoor pool for winterization.

1. Preserve the pool until the first severe frost.
2. Do not leave the outdoor pool empty for the winter.
3. Install expansion joints in the pool before the water freezes. As compensators, objects are used that can compress with an increase in external pressure and take on the load from the ice formed in the pool.

The main rule is to have time to mothball the pool before the first serious frosts.

The outdoor pool should not be left empty for the winter. The point is not only that under the ice the appearance of the lining of the bowl will be better preserved. The main danger is the change in the volume of the soil surrounding the pool when it freezes. Freezing and thawing soil in the immediate vicinity of the pool dramatically increases the load on the walls, which can lead to the destruction of the concrete and metal elements of the hull. Therefore, the presence of frozen water inside the pool partially compensates for the mentioned loads.
What has been said does not mean that conservation is carried out without draining the water that you have been using all summer. It is not worth freezing this water for the winter, even if it meets all the requirements for the main indicators of water for swimming pools. This water must be completely drained. Before re-filling with water, the bottom and walls of the pool must be thoroughly cleaned. This is done in an empty pool using brushes and special cleaning products. Cleaning products are recommended to be used in full accordance with the nature of the internal coating of the pool.

This applies especially to film coatings. Wall and bottom cleaners are usually quite aggressive chemicals, so the process must be carried out in compliance with safety regulations, work in rubber boots and gloves. A viscose sponge or a plastic brush with hard bristles is used as a tool. After cleaning, the entire inner surface of the pools is thoroughly rinsed, and then the remaining water is removed manually. At the same time, deposits are removed from metal parts that are in contact with water (lamps for spotlights, stairs, handrails, etc.)
While the pool is empty, the lighting devices built into the walls are dismantled. The protective glass is removed, the device is removed from the niche, the wire is brought up over the edge of the pool and carefully insulated.
Preservation water is filled initially to the previous level.

When the filling is finished, the filtering system can be preserved. The pool filter enters backwash mode. In this case, the instructions for this process must be strictly observed, since, for example, switching the filter valve while the pump is running can cause system breakdowns. After the end of the backwash, the filter is put into compaction mode. Then – in the normal filtering mode.
At this time, a special preservative is added to the water, such as Puripul from BAYROL, which prevents the development of algae. It ensures the purity of the water in case the expected frosts are delayed. Conservation water with an anti-algae agent dissolved in it is filtered in the normal mode for two to three hours.
After that, part of the water from the pool is drained until the level drops 10 cm below the side nozzles.

The next step is to install expansion joints for freezing water. As compensators, objects are used that can compress with increasing external pressure. These can be plastic canisters filled with air, slightly inflated car tires or foam bars. The compensators are sunk under the water of the pool with the help of weights in the form of sandbags tied to the compensators. The best option is to sink plastic canisters in the central part of the pool and place foam plates about 5 cm thick along the sides of the pool at a distance of 5-10 cm from the side. The foam is distributed evenly, and its total length in plan should not be less than half the perimeter of the pool. When tying loads, do not use metal wire. A strong synthetic twine works best.

After installation of the system for compensating the volumetric expansion of water in the piping of a stationary or frame pool, all parts of the hydraulic system are dismantled – a counterflow device, a filter unit, a heating system, etc. Parts of the hydraulic system that are not subject to removal are freed from water, and the free ends of the pipes are isolated with plugs. Styrofoam plugs are installed in the niches of lighting fixtures, in the niche of the skimmer and in nozzles located above the level of conservation water. The filter is disconnected from the hydraulic system. The water from the filter is drained, the sand is removed and transferred to another container or to a linen bag. The filter housing is cleaned of sand residues and removed for winter storage.

The last step is to close the water table. Best for this purpose are special coatings that are used all year round. In summer, they protect the pool from pollution and cooling at a time when the pool is not in use; in winter – serve as the last measure of conservation. If the top cover is initially intended to be used in winter, it must be adequately strong and able to withstand the weight of the snow cover. It is not recommended to use wooden shields and metal structures resting on the sides of the pool to cover the water surface. The purpose of conservation, we recall, is to minimize the mechanical stress on the hull structure during a long winter downtime. Ice in a freezing pool should be protected, in no case should it be crushed, as ice fragments can damage the internal coating of the pool.

The pool is reactivated after the ice has completely melted in the spring.

Useful information

tips for winter conservation

The outdoor pool is a great place for the whole family to relax. But you can use it only in the warm summer period. And then preparation for the winter or, in other words, conservation is required. The bowl should be securely sealed until the first frost.

Frame pool winterization

Prefabricated frame pool – a common variety. It consists of a frame, usually made of metal (rarely wood), of a plasticized PVC inner bowl that holds water. This type of pools is frost-resistant and cannot be dismantled for the winter, while preparatory work for its conservation cannot be dispensed with. It must be carried out by specialists.

Main steps:

  1. Drain all water. Before this, you need to perform several actions: eliminate disinfectants; flush the filtration system; drain the water.
  2. Cleaning the bottom, walls. A soft-bristled brush or sponge is used to clean the walls from dirt using special detergents. When performing such work, you should wear gloves, boots, rubberized clothing, close your eyes and face. The solution must not be allowed to leak, as it can poison the soil around the pool.
  3. Disassembly of systems. For the period of conservation, it is necessary to dismantle the equipment: filtration, heating, disinfection systems. It is recommended to drain the water from them, wash, dry. If the equipment cannot be removed, then it is important to drain the water from it, dry it, install special plugs. Particular attention should be paid to lighting devices that need to be carefully removed, their glasses removed, and the wires insulated.
  4. Filling. One of the final stages is filling the bowl with water with disinfectants and preservatives. This significantly reduces the growth of bacteria, prevents blooming and solid precipitation on the bottom and walls of the bowl during the conservation period, which greatly facilitates the preparation of the pool for the new season.
  5. Installation of compensators. These objects take on an expanding volume of frozen water. Any hollow objects, for example, plastic bottles, can serve as compensators.

The last stage of conservation is the installation of the coating. The main requirements that apply to it: high-quality material that can withstand the severity of snow and temperature fluctuations. It should be noted that conservation can only be carried out for metal-framed, reinforced concrete and wooden-framed bowls, which are frost-resistant.

Preservation of the pool without draining the water

Many people are interested in the question: “Is it possible to winterize the pool without draining the water?”. This is possible when it comes to metal-framed, reinforced concrete and wooden-framed bowls with no bottom drain. In this case, if the surface, if the walls and the bottom of the bowl do not have stubborn dirt, and the water has a clean and transparent state, the bottom of the bowl is cleaned with a vacuum cleaner, then the Ph level in the water is leveled, shock disinfection is performed. After that, the “mirror of water” is lowered by 10-15 cm below the level of all embedded elements in the bowl (skimmers, nozzles, spotlights, etc.), the spotlight lamps are dismantled and the cables are insulated, filtration systems, disinfection heating for those who they are, according to the scheme as described above in the “Disassembly of systems” subsection. The final moment will be the addition of a preservative composition to the water, hydraulic lifters and covering the surface of the water with a winter blanket. The action of the winter preservative composition is aimed at preventing blooming and precipitation of solid deposits on the bottom and walls of the bowl until the water freezes and after it thaws until the start of operation.