Guide to Winterizing Your Swimming Pool

Winterizing a pool is a crucial part of keeping it safe and usable throughout its intended lifespan. You don’t need to do this if you have an indoor pool with a temperature-controlled environment, or if you live in a temperate region where it never gets too cold to start with.

However, you do need to winterize things if you have an outdoor pool in areas where freezing temperatures are typical during the winter months. Here’s what you should know about this process.

Why It’s Important To Winterize Your Pool

Winterizing a pool is essential for avoiding a variety of problems. Here are the most common threats winter poses:

Cracked Sides

Frozen water expands, and when it’s in a pool, that pressure could put cracks in the pool itself. These cracks can be difficult and expensive to repair, so preventing this is one of the main goals of winterizing a pool. Fortunately, this usually isn’t a threat if the water is low enough, and we’ll discuss that in more detail below.

Burst Pipes

When water freezes inside of pipes, it can break them in the same way it can crack the sides of pools. Burst pipes are challenging to locate and usually even harder to repair than cracks in a pool, so many people try to empty the pipes before plugging them up for the winter.

Personal Safety

The idea of converting a swimming pool into an ice-skating rink may sound appealing on paper, but it can also pose a serious risk to personal safety if done improperly. Any exposed ice may not be thick enough to move on, and anybody who decides to walk across a frozen pool may end up falling in.

Chemistry Troubles

Cold and freezing temperatures can affect your pool chemistry. While the temperatures usually inhibit the growth of algae and bacteria, improperly winterizing your pool could throw the chemical balance off and lead to structural damage.

When To Winterize Your Pool

You should winterize your pool before temperatures drop below freezing in your area. Unfortunately, cold snaps can be unpredictable, and homeowners like you don’t always have the opportunity to winterize things properly before it gets too cold outside.

In these cases, the best option is to keep your pump running and winterize your pool as soon as possible. Leaving the pump on will stop the water from freezing, but this could still cause problems if there’s a power outage, so it’s better to winterize than leave the pump on all winter. If you’re in really cold temperatures, you can also add antifreeze to your lines.

If There Are A Lot Of Trees Around

If trees surround your pool, you should winterize and cover it before the leaves start falling in earnest. Otherwise, it’s going to be a lot of extra work to get all the leaves out of the pool.

Step-by-Step Process For Winterizing An Inground Pool

Follow these steps for winterizing your inground pool.

Step 1: Thoroughly Clean Your Pool

Remove all debris from the surface, the bottom, and the sides of your pool. You may need to do this manually because manufacturers often recommend taking automatic pool cleaners out of the pool sometime before temperatures start to drop.

Be thorough while cleaning. Any organic material left in the pool could stain it, so the primary goal of this step is getting the entire pool as clean as possible.

Step 2: Check Your Pool Chemistry

The next step for winterizing your pool is checking the pool chemistry. In particular, look at your pH, overall alkalinity, and calcium hardness. If these are all within the appropriate ranges for your pool, you’re ready to start winterizing. If they’re not correct, adjust them as necessary.

Some people shock their pool before winterizing. If you haven’t done that in a little while, do it before checking and adjusting the rest of your pool chemistry.

Step 3: Add A Winterizing Chemical Kit

Many pool stores sell winterizing chemical kits that should last for the entire season. Use one of these in your pool and follow the manufacturer’s directions exactly.

Never mix chemicals or cleaners unless directed to do so. Pool chemicals are generally safe when used as directed, but combining them incorrectly could be dangerous or even deadly. This is particularly true if you’re also using household cleaners in or around your pool.

In The Swim Pool Winterizing and Closing Chemical Kit - Up to 15,000 Gallons
  • Unlike chlorine-based winter kits that reduce the effectiveness of algaecide and other pool winterizing chemicals and can stain, bleach or damage pool...
  • In The Swim winter kits include a slow-release winter floater filled with a powerful non-chlorine oxidizer.
  • No staining, no bleaching... just clean, sanitary water
  • Includes pool winterizing instructions.
  • Pool water temperature should be at 65 degrees F or below before winterizing.

Step 4: Let The Pool Chemicals Filter

It’s tempting to continue winterizing right away, but for most pools, that’s the wrong decision. Instead, let all of your pool chemicals cycle and filter through the pool for 24 hours. This helps ensure that your chemicals obtain maximum coverage, and therefore your pool receives maximum protection.

Step 5: Lower The Water Level

At this point, it’s time to start lowering the water level of your pool. For most pools, this means lowering it below the mouth of the skimmer and return lines. Fiberglass pools shouldn’t go that low, but lowering the water below the skimmer for other pools will help protect it if your water starts freezing.

Some pools can benefit from plastic dams that go in front of skimmers to keep water out. These are also useful for holding up covers like tarps and liners, so consider using them even if you’re lowering your water level.

Do not lower the water too far. Doing that can result in hydrostatic pressure, and over time, that can cause severe damage to pools.

Step 6: Clear The Pump And Filter

Remove any plugs, then pump water entirely out of your pump and filter system. This includes any heating elements you may be using. We don’t want to leave too much water in the pipes during the winter, so the more you can get out, the better.

Many people use an air compressor to push the water out of the pipes. If this is viable for your pool, go ahead and do it.

Once you’re done clearing the pump and filter, plug all the lines and add a Gizzmo to your skimmer. If you’re not familiar with these devices, Gizzmos are special tools that help absorb the expansion of freezing water to protect your skimmer system. It’s always better to be safe when winterizing, so be sure you use them.

Step 7: Take Everything Out

At this point, remove any handrails, ladders, or other components that are still in the pool.

Step 8: Cover Your Pool

Finally, cover your pool with an appropriate pool cover. Many people use options like vinyl or tarps. You may need to place some type of pump in the middle of it to remove rainwater that could otherwise weigh the top down.

Step-by-Step Process For Winterizing An Above Ground Pool

Winterizing an above ground pool is a little different from winterizing an inground pool.

Step 1: Clean Your Pool As Thoroughly As Possible

Like inground pools, it’s best to start by cleaning your pool as thoroughly as possible. This involves clearing the top, scrubbing the walls, and getting everything off the floor of the pool. The more thorough you are, the better.

Step 2: Adjust The Chemistry

Measure your pool water’s chemistry, then adjust or shock it as needed to get the chemistry as close to perfect as possible. For winterizing, it’s generally better to be on the high end of each chemical range. The chemicals will wear out eventually, but if they’re relatively high to start with, they’ll last longer.

Adding an algaecide is optional, but usually a good idea.

Step 3: Clear The Lines

Once you’re done adjusting the chemicals, it’s time to clear the lines in your pool. This is usually as easy as disconnecting them, letting the water run out, then air-drying them, and storing them out of direct sunlight. The drying part is especially important to help prevent the growth of mold.

Step 4: Protect Your Skimmers

Most above ground pools work best with a skimmer plate, which is a solid cover that seals the skimmer away from the pool. Adding one of these means you won’t have to lower the water level, either, which is nice for saving time.

If you don’t want to plug it up, take some water out of the pool and make sure it’s free enough to drain if there’s any rain. Ideally, rainwater won’t get in at all, but it’s always better to be safe.

Step 5: Protect Your Pump And Filter

For the pump, remove all of the drain plugs and let them drain, then take out your pool pump, hoses, and any additional components. Store all of them together indoors, so you don’t have to go hunting for them when Spring arrives.

For filters, follow the manufacturer’s directions for winterizing them. Different types of filters need different care, so there are no universal guidelines for this part of winterizing your pool.

Step 6: Remove Accessories

Accessories include toys, pool ladders, and anything else you might leave in or around your pool while it’s open. Thoroughly clean them, then store them in a dry area away from sunlight.

Step 7: Install A Pool Pillow

Sometimes known as ice compensators, pool air pillows help to balance out the weight of any ice and snow that fall on top of your cover. The pad should be placed around the middle of the pool and ideally kept there somehow.

Only inflate the pillow to about 55% of its maximum capacity. It’s tempting to try and inflate it all the way, but leaving some give in the pad allows it to compress under the weight of snow without breaking.

Step 8: Put Your Cover On

Finally, it’s time to put your safety cover on. Some people use solid covers while others use tarps or other thinner tops. Whatever you want to use is fine as long as it works. Just make sure you don’t weigh it down with anything that could damage your cover, your liner, or the pool itself if it falls in. (This means bricks are a terrible choice.) Try to keep the cover clean and dry throughout the winter.

If you need any additional materials for completing all the steps above, a typical pool closing kit should have everything you need.

Need Some Maintenance Help?

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And that’s it! Any questions? Shoot us a note. Also be sure to check out our guide on opening your inground pool once the warmer months roll around.

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