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Swimming pool winterization

Taking proper care when closing a swimming pool will not only protect your client’s investment, it will also make opening the pool the following spring relatively simple.

By John Puetz

Keeping pool water clean, clear, healthy and inviting to bathers seems to carry its own rewards when the weather is warm and sunny. However, when the cool winds of autumn start to blow, it seems to be harder to think about pool care. This article will explain the process of winterizing swimming pool water, as proper care in closing the pool will not only serve to protect your client’s investment, but will hopefully make the task of opening the pool the following spring relatively simple.

Be proactive in the fall

If you are in the service/maintenance industry and depend on opening/closing pools as a portion of your livelihood, it makes even more sense to do as much as possible in the fall. Think about it; in the fall you will likely have more time at your disposal to close pools and no one is likely to be pressuring you to get the job done. The more you do now and the better you do it, the pool will be much easier to open in spring when customers are anxious to start swimming.

The approaches to pool closing vary widely. Some parts of the country experience severe freezing temperatures in the winter, while others remain fairly moderate and even warm. Pool construction also varies, from plaster to vinyl to fibreglass, while some are above ground and others inground—each has its own closing quirks. Service people also vary in their approach to winterizing. However, regardless of the location, pool type or approach taken, closing will provide clean water in the spring if done properly.

This article cannot cover all pool closing variations, but it will provide an overview of the essential stages of winterizing, along with the products that can be used to help make the task easier and more reliable.

Two areas of concern

Before any type of water treatment is performed, the pool should be given a thorough cleaning and prepared for winterization. In this process there are two basic areas of concern.

The first is to protect the plumbing and equipment from cold weather damage, especially in severe winter climates. To prevent freeze damage, care must be taken when draining water from the pool’s plumbing and equipment. How this is done will vary widely depending on pool type and the equipment itself. In general, you will want to blow out the lines and drain water from all pumps and filters. Once the lines are clear, specialized antifreeze (which is safe for pool use) can also be used to prevent plumbing lines from freezing; however, this approach is somewhat controversial. Some argue that if you empty the lines completely, there is nothing to freeze and thus cause harm, while other professionals swear by antifreeze, as it is a way to be certain any residual water that freezes will not cause any damage.

The second concern is to keep the pool water algae-free and as clean as reasonably possible.

Step one

Balancing the water chemistry is extremely important when closing the pool for the winter.

Balancing the water chemistry is extremely important when closing the pool for the winter. It is best to adjust the water into the following ranges:

  • pH, 7.2-7.8;
  • total alkalinity (TA), 80-150 parts per million (ppm); and
  • calcium hardness, 150-400 ppm.

It is not unusual to have calcium hardness levels higher than 400 ppm and it is not always easy or necessary to lower this level if it exceeds this range. It is always best to use a sequestering agent, regardless of calcium level, but especially if hardness is high. See more information on sequestering agents under step five.

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