How to Winterize Your Hot Tub – If You Want To

Published : October 28, 2019

Winterize Spa

A couple weeks ago, we asked hot tub owners if they prefer to use their hot tub in the winter or shut it down for the cold season. While it seems like many hot tubbers enjoy the idea of getting into their spa when the temperature drops – or better yet when the snow starts to fall – there are those who prefer to put a lid on it.

While the decision to close their hot tubs for the season isn’t as automatic as it would be for pool owners, approximately one in four hot tub owners elect to close their spa during winter according to the consumer website The factors they consider include: whether they are going to be home for the winter? If their hot tub is enclosed in a gazebo or under a roof? And if it is easily accessible via a covered walkway?

Whether or not you want to use your spa when there could be snow on the ground, you need to prevent freeze cracks from developing through the cold, harsh winter. You don’t want stagnant water to expand and contract in and around pipes, jets and other components after it freezes and subsequently thaws. This can be accomplished a few different ways and this article will explore the proper way to keep water in your spa during the winter, or close it. It also will focus on key chemical and water care tips that are unique to the cold season and inclement weather.

Since more people want to enjoy the benefits of hot water therapy when the mercury drops, let’s start there:


Keeping Your Spa Running Through Winter


If you choose to keep the water in the hot tub, you have a couple options for ensuring your spa makes it through the cold without incurring any major problems. Either you intend to use the spa in the winter or you just want to prevent a potentially damaging freeze.


Enjoying Your Spa in the Winter


Think about this: every ski resort in North America has hot tubs and spas running in the winter. Why? Because it’s a great way to unwind and relax after a long day on the slopes. So why not enjoy those simple pleasures at home if you own a spa?

There’s no feeling quite like taking a soothing dip in hot water, while the temperatures drop to around freezing outside. And there’s something to behold if you are lucky enough to sit outside in a bathing suit while snow falls on your head – unless you wear a hat, which is a sound idea to help regulate your body temperature.


Even in the cold, you need to keep your spa water values at the same general levels to ensure an enjoyable bathing experience in crystal clear water. You should target the following readings with standard test strips: pH 7.2 to 7.6, chlorine 3 to 5 ppm (or bromine 4-6 ppm), Alkalinity 80 to 120 and hardness 100 to 250. Adding SilkBalance water conditioner that buffers pH and Alkalinity values from week to week is a good idea for an even easier spa water care upkeep in the cold.

Each time you use your spa, your sanitizer levels will quickly drop, so be sure to add chlorine or bromine regularly and consider using a non-chlorine monopersulfate shock oxidizer such as Shock Gems every time you exit the spa. This will help to immediately neutralize organics such as body oils and prevent unwanted proliferation, thereby helping your sanitizer work more efficiently and last longer.

Pay attention to the water temperature a bit more closely in the winter. Set your spa to auto heat mode or an equivalent setting that allows it to run at least 15 minutes every hour. If your spa is equipped with a 24-hour circulation pump, this is a moot point because water is constantly circulating. It’s also a more energy efficient practice to keep a consistent setting at your favorite temperature than to turning it way down and then back up again later. Keep in mind that in the event of a total power outage, it will take 3-5 days for a spa heated to 104 degrees F (40 degrees C) to completely freeze.

There are a few external considerations when using the spa in frigid temperatures. A thermal spa blanket that floats on the water will vastly help reduce evaporation, while a vinyl cover spray can help protect the hard cover through the winter. Don’t be afraid to knock the snow off your hot tub cover before lifting it. It’s better on the ground than in your water messing with the clarity.

If your cabinet is made of real wood, use a weatherproof sealer or linseed oil to prevent the wood from absorbing moisture, which can freeze and lead to warped cabinetry.

Finally, slippers and robes that may not be necessary in warm weather, will certainly be appreciated once you exit the hot water, so be sure to have them readily available upon exiting the spa – along with a towel that has been hung up off the cold ground.

Preventing Your Spa From Freezing, Without Using It

If you know you are not going to brave the elements and head outside for a soak when there is snow on the ground, you can keep it heated at a much lower temperature than you would for bathing. Most people enjoy their hot tub water at ±102ºF [39ºC], but you can save energy by turning the water temperature down to ±60ºF [15ºC] and ensuring the circulation pump is operating.

Before your last soak of the season, make sure you adjust the pH and Alkalinity of the water. A concentrated shock treatment along with a winter algaecide are also good to add, since the water won’t be getting used.

To make sure the pipework remains clear, periodically run the jet pumps to circulate the water. The latent heat in the spa or hot tub will also maintain safe temperature to prevent freezing. Check to see if your hot tub has a freeze protection mode or can be set to filter the water more often. In many spas, a “standard” setting or “F3” filtration option should do the trick to keep the water circulating and most modern hot tubs have a built-in sensor that turns the heater on if temperatures dip below freezing.

Even though there won’t be anybody using the spa, evaporation remains an issue – especially in the cold. Make sure the water level doesn’t drop below your highest jet. Low water levels could cause the spa to stop working.

Maintaining the correct water chemistry values is still a good idea. Your regular routine of checking with test strips should wane a bit without introducing any organics into the water, so periodically peak at your hot tub – perhaps when there’s not a foot of snow on top – and continue to add a sanitizer like chlorine at the very least. Remember the goal here is water circulation, but wouldn’t you have peace of mind knowing the water is at least oxidized? You can decide come spring whether to drain and refill after using a plumbing purge product such as Clean Start to clear the winter pipes – or whether the water made it through the cold in good enough fashion to enjoy in the spring. Again, consider using SilkBalance or SilkBalance Gems that will prevent spikes in pH to help the water last longer, especially since the total dissolved solids will be kept at a minimum.

After adding chemicals periodically or topping of the water line, make sure the spa or hot tub cover is tightly in place to retain as much heat as possible.

Remember, the colder it is outside, the longer it will take for your water to heat. Hot tub heaters are not like your flat top stove. They don’t heat instantly, rather they bring the water temperature up at a rate of only a few degrees per hour.

Winterize Hot Tub

Winterizing Your Spa

Improper winterization methods are the main causes for damage to hot tubs and spas installed in cold weather climates. The freeze results in varying degrees of damage and can be expensive to repair. This is a DIY – do it yourself project, but if you are leery you can contact your local spa retailer or hot tub service professional for assistance.

Follow These Steps to Winterize Your Spa:

  1. Turn off the power to the unit – at the breaker box and the main circuit on your home panel.
  2. Attach a garden hose to the bottom spout and drain the water – keep the drain open all winter. A submersible pump or shop vac can help remove the remaining water in the foot well and in the plumbing lines. Towels can be left in the foot well to soak up lingering water.
  3. Remove the filter(s) and dry the filter compartment. Store the filter(s) in a dry location until spring.
  4. Access your spa’s equipment behind the cabinet and loosen/unscrew all visible quick disconnect fittings on both sides of heater and pump(s). Leave these fittings disconnected to allow water to come out all winter. Remove any other drain plugs to prevent cracking.
  5. Blow out any residual water from the jet piping using a reversible shop vac or air compressor to clear each jet as best you can. If you have topside air controls, close them.
  6. SPA WINTERIZING WATER CARE CHEMICAL TIP: Do NOT use antifreeze in acrylic spas. Antifreeze is necessary only if you were going to leave water in the pipes. If you choose to leave water in the plumbing lines, there are better alternatives. (See “Keeping Your Spa Running Through Winter” ) Antifreeze is very problematic to completely remove before opening your spa in spring.
  7. Cover your entire spa completely – including the cabinets. You can keep the hard cover on the spa, but the seam in the middle is not completely waterproof and could allow water to seep in. Place an additional winter spa cover or large marine-grade tarp on top and drape it over the edge, down to the ground and cinch it tightly around the cabinetry at the base with a cable/rope/bungee. Then secure the extra cover or tarp down with bricks or stakes. You also may choose the place an inflatable air pillow under the winter cover to provide a tapered arc over your spa to encourage rain/sleet/snow/ice runoff. A winter cover that encompasses your spa also helps prevents critters from seeking shelter in your hot tub.


When spring comes around, you will be happy you took such methodical care of your vessel. Consider starting the new hot tub season with a quick fill followed by a Clean Start plumbing line purge, drain and refill just to ensure there’s no lingering buildup in your spa’s plumbing. This step will help remove the winter water and help clean out the maze of a water system underneath your spa. Your hot tub will thank you by operating more efficiently.


Usually spa owners decide to reopen their hot tubs when they get the Spring cleaning itch and it’s warm enough outside. After you purge the old water, clean your spa shell with a cleanser that won’t damage the acrylic and give your spa a clean buff before refilling with fresh water.


The water values you want to maintain are the same year-round: pH 7.2 to 7.6, chlorine 3 to 5 ppm (or bromine 4-6 ppm), Alkalinity 80 to 120 and hardness 100 to 250. SilkBalance and SilkBalance Gems can help prevent spikes in these values, making water care simpler.


Whichever route you choose for your spa during winter – to use or not to use it – following the procedures outlined above will help you enjoy a fresh start in the Spring and provide added peace of mind that you successfully nurtured it through the coldest season.

By Eric Vician
Director of Promotions & Key Accounts

Eric Vician of SilkBalance Hot Tub Water Care



EDITOR’S NOTE: Excerpts from this blog originally appeared in Pool & Spa Marketing Magazine in an article written by SilkBalance. For a list of articles SilkBalance has contributed to the magazine and for more water care FAQs, visit:

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