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Pool Winterizing Guide – When and How to Do It

A s the cold weather approaches and you don’t spend your time swimming anymore, comes the time to winterize the pool. The necessity for this procedure is quite straightforward considering that the cold weather would produce chemical and physical damage to the pool and its components, something that you can actively prevent by closing the pool.

Thankfully, this is a simple procedure that you can do on your own and does not require any extensive practices. Here, we will go over the winterizing steps to aid you with this routine chore you must undergo each year. A successful closing leads to a good pool opening, so don’t neglect it as you save money in the long run and preserve the costly equipment.

What you should know from the get-go is that in-ground and above-ground pools alike require winterizing. For the latter, this is needed if you don’t take it down at the end of the swim season.

What Is Winterizing?

This is the off-season maintenance that you must follow through with to safeguard the pool and its parts from the freezing temperatures. As you likely guessed, it implies closing off the pool following specific proceedings to keep it safe from climate changes until the sun warms everything up again, and you restart the swimming season. Environmental and climatic conditions affect the timing and procedure, but generally, the techniques and methods we will provide here apply for all types of in-ground and above ground pools.

Why Is Pool Closing Needed?

Temperatures drop considerably in autumn and winter. As the weather shifts from the pleasant warmth of summer, you will start to use the pool less and less until you won’t do so at all. At that moment, you should close the pool to preserve water quality, protect the surfaces, and secure the expensive equipment. By properly following through with winterizing, you avoid green algae stains, frozen tiles that damage, burst pipes, and costly broken pool equipment, to name a few.

Tip: When summer comes, you will have to reopen the pool. Follow the pool winterizing steps here to avoid making mistakes as this can lead to costly and time-consuming opening when the temperatures rise once more.

When Should You Winterize the Pool?

There are two factors to take into account when it comes to timing – temperature and falling leaves. If you have trees in the proximity of the water body, as soon as autumn comes and they start to fall, chances are that some will end up in it. This means that you will end up spending time skimming the pool and cleaning it more than you should, and for no actual reason because you likely won’t swim by this point anymore. Thus, you can use the falling of the leaves as guidance for when you can proceed to close the pool.

Temperature is the most common factor to use as guidance for the procedure, though. Depending on where you live, you will have to follow through with this upkeep task earlier or later in the year. If you live in an area with high temperatures all year long, like Florida, chances are you won’t ever have to close it. Lucky you!

Is the area you live in cold and you want to extend the swimming pool season? Then install a pool heater, and you will enjoy an estimated one-month addition to the pool season!

Turning back to the issue at hand – when to close the pool according to the weather. When outdoor temperatures drop under -1°C or 30°F at night, it is your signal that winterizing is required. Why is this needed? Well, the pump might continue to move the water, preventing freezing. However, if there is electricity loss at nighttime and the water freezes in the filter, pump, or plumbing lines, damage will ensue. This is what you must avoid and why you must guide yourself after nighttime temperatures.

If you use a robotic pool cleaner for pool upkeep, read the instructions regarding the operating temperature threshold. You will likely have to “retire” the cleaning device before winterizing, but considering that this protects your investment from damage, it is a mandatory task.

Step-by-Step Guide

Now that you understand what winterizing is, why it must be performed, and when the right moment to do it is, let’s move on to the steps that you need to go through. Make sure to not skip on any of the following tasks and carefully check everything on the list to make sure that you do a good job and keep your pool and the gear safe from the freezing temperatures.

Step #1 – Clean the Pool

If you have a robotic pool cleaner and you used it routinely up to now, a final cleaning cycle on its part should suffice. If not, use a brush to manually scrub the walls and floor of the pool (attach it to a telescoping pole) so that you remove any sediment that might lay on these surfaces. Then, vacuum the gunk and debris to clear the water.

Why do it yourself when you can have a clean pool without any effort? Look into the SmartPool 7i reviewed here to see how this robotic cleaner can keep the pool clean without requiring your intervention in the slightest.

Step #2 – Testing and Chemicals

Use a water test kit on a sample to verify factors related to water balance, including pH and alkalinity. While it is not in use, without a proper chemical balance of the water, the pool can corrode, and scale might appear on surfaces.

Keep the chlorine level under 5 ppm so that it won’t alter the additives you utilize. If the level is in check, and add the following winterizing chemicals (not all are needed; check which ones you need and only use those):

  • Algaecide: This is a mandatory additive as it prevents algae spore growth while the pool is not in use. Double the dose in case there are chances for debris and gunk to enter the water in the meanwhile.
  • Metal sequestrant: If the water comes from the well or it tested high for metal levels, use this additive to suspend the particles, preventing surface stains and oxidizing.
  • Pool antifreeze: Chances are that you won’t get all the water out from the pipes. A safe alternative to avoid this is to use antifreeze intended for pools. One that is rated to -12°C or 10°F should suffice, but if temperatures get lower in your area, check the product description to match its capabilities to your needs.
  • Use a specialized sanitizer: There are special additives designed for closed pools that take months to dissolve. Use one of these instead of chemical tablets as their distribution might not be as optimal for winterizing.
  • Pool enzymes: These additives help the algaecide in its performance as they also tackle organic impurities.

Step #3 – Superchlorinate the Pool

Preferably 24 hours before you install the cover and close the pool, superchlorinate it. Add the shock according to instructions, and if you have signs of potential algae growth, double or even triple the dosage. Run the pump overnight for even distribution of the treatment. The next day, test the pool balance to see if everything is in check.

Tip: Shock the pool during the night so that the sun won’t be able to tamper with chlorine levels before the treatment makes its effect.

Step #4 – Reduce the Water Level

The water level should be under the tile border before you proceed to close the pool. If it is not at this level, take out as much water as needed to rectify. Check the instructions of the pool cover you intend to use as it might contain instructions regarding the proper water level too. If so, follow those guidelines to make sure the water provides the needed support for the cover.

Step #5 – Cleanse the Filter, Pump, and Clear the Lines

Make sure there is no debris and bacteria left in the filter throughout winter so that you don’t damage it. For cartridge filters, wash them with a specialized cleaner, rinse, and let them dry before storage. With sand filters, backwash thoroughly and drain the water before storing away the plugs. In case you have a D.E. filter, either use a specialized cleaning solution or backwash it.

You must also either blow out the lines or alternatively use antifreeze. If you opt for blowing, make sure that you remove even the last drop of water from the filter, pumps, and pipes so that you hinder ice damage throughout the cold season. What does blowing involve? Simple, blast air through the plumbing. Follow through carefully with the procedure as it can do significant damage.

Recommendation: Hire a professional if you don’t want to use antifreeze, and you simply want to blow the lines as a single mistake can end up costing you a lot of cash in restoration.

Step #6 – Store Away the Accessories

Remove and store away all accessories like rails and ladders. Otherwise, these could rust because of chemical damage to the finishes, and the rust will inevitably pollute the water. These items can pose an issue even for properly securing the pool as they won’t allow the cover to sit in place as it should. Don’t forget to remove return line fittings (even those of the automatic cleaner) and store them away until you reopen the pool. After removal, clean and dry the accessories. Bear in mind that you must deposit them somewhere clean, dry, and not in direct sunlight.

Step #7 – Install the Cover

Depending on how harsh the weather gets in your area, you can pick one of two different pool cover types. Go for the regular winter cover if temperatures are not that harsh, and for the safety pool cover if you have animals or children that you want to prevent from falling inside, or if winter is particularly aggressive.

Pool covers are not exclusive to wintertime use. You can utilize a solar pool cover to upkeep a clean body of water easier during the swimming season as it will block debris from entering.

Should You Contract a Professional?

First, let’s go over costs. When it comes to pool winterizing services, expect professionals to charge from an estimated $150 to $400 for this procedure. Pricing varies depending on the size of the pool, as well as its type. For example, small above-ground pools tend to cost considerably less than larger-size in-ground pools. The location and pool condition also affect the final price.

As you can see, this is a viable DIY project that does not require the most extensive knowledge in pool maintenance. However, a single wrong step or overlook a part of the process can lead to a disaster, so if you are not confident that you can do a good job, avoid the DIY route.


An extensive procedure but mandatory for proper upkeep, pool winterizing can be performed by you alone (maybe ask a friend for help when you install the cover, though). If you do feel that the procedure is too much for you at the moment, call in a professional, and pay attention to how they proceed to know what you should do next time. If you overlook it, expect to pay even up to thousands in pool system and equipment repairs caused by frost damage. Thus, you can see why this is not an optional procedure for any pool owner.

Want to learn more about pool maintenance? Then read this article to learn how to handle black algae to solve the issue if it ever appears.

Braden Ewing
Braden Ewing
Braden is the editor-in-chief at, as well as the oldest member of the team. He has previous experience in sales as he worked at a local electronics store. While there, Brandon first encountered robotic devices for household use and become passionate about the subject. Since joining the team, he provided expertise regarding the latest technologies in the domain of automated cleaners, conducting proper research at all times to provide users with content that is relevant.

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