Closing Time - Part 3 - Last Step

winter pool closing

It’s not quite winter yet, but the cold weather is rolling in. This is the perfect time to pop the big question: to close or not to close your pool? You may not even have a choice, depending on your local climate. If you live in a colder climate, leaving your pool open in the winter months could lead to your water freezing, causing massive (and expensive) problems in your lining and your pool’s system. In milder climates, you might be able to get away with performing some basic maintenance steps to leave your pool open.

If you don’t plan on closing your pool for the winter, here are some tips to ensure you maintain crystal clear water until it’s time to jump in again:

  • Solar blankets keep your water above freezing, even when it’s freezing
  • Pool heaters can extend your pool season by keeping your water warm
  • Cleaning your pool regularly keeps it clear of dirt, leaves and debris
  • Balanced pH and chlorine levels ensure your pool is free from algae and bacteria
  • Running your pump on a regular basis to keeps your water from freezing, or even better
  • Install an automated freeze protection system to turn your pump on automatically when it starts  getting too cold

If you’re planning to only partially drain your pool and then cover it for the winter, the closing process isn’t too difficult. After balancing your water, cleaning your pool, and checking equipment, follow the next steps to close your pool for the winter.

Step 1: Add winter chemicals

Once your pool is balanced and cleaned, add the winterizing chemicals. If you are using a winterizing kit, follow the instructions on the kit to add the chemicals. If you are not using a winter kit, here’s a quick checklist for adding winter pool chemicals, which will help water to be cleaner when you open your pool for spring:

  • Shock the pool using extra strong chlorine or a non-chlorine substitute to kill microbes.
  • Add an algaecide to prevent algae growth as well as organic staining through offseason.

Quick Tips:  

  • This process is sometimes carried out after lowering water levels below the skimmer, so the concentration is stronger.
  • Remember not to add algaecide and shock the pool at the same time. Shock the pool 4-7 days prior to closing pool and then add algaecide before you cover the pool.
  • If you use a stain  & scale treatment, add this to the pool before lowering the water, so that it is mixed very well in the pool

Step 2: Drain your pool water below skimmer

You can partially drain your pool water below the skimmer by turning off the filter system and setting filter to backwash. Set valves to main drains so that you are pulling water from the main drains at the bottom of the deep end and turn your filter on. Then, shut off the filter system, turn the multiport valve to ‘waste’ and turn it back on. Let it run and drain your pool just a few inches below the skimmer. The water is lowered below the skimmer according to type of pool cover you’re using.

  • 6-12 “below the skimmer for mesh safety covers
  • 4” below the skimmer for solid covers.

Step 3: Blow pool lines

You can use a simple shop vacuum, an air compressor, or an air blower to blow out all the water from each and every return line throughout the pool, including cleaner lines. The water can also be blown from the skimmer, through the equipment, back into the pool. Use a gizmo to seal the skimmer throat to prevent skimmer from cracking. You may also use non-toxic swimming pool antifreeze to ensure that any water left in the lines doesn’t freeze. Check if water is blown out of pumps, pipes, filters, heaters and chlorinators to protect it from freezing as well. If you’re not sure about how to blow out the lines and drain all the equipment, text us at 415-299-8082 to schedule an appointment with our pool service technicians.

Step 4: Put on a winter safety cover

Finally, it’s time to cover up the pool! This process not only keeps the pool away from debris and algae staining during winter but also protects people or pets from accidentally falling through the cover into the water. Use a clean, durable pool cover and get the cover set in place. Place your weights around the perimeter of the pool.

Quick Tips:

  • Make sure that all equipment is shut off before you cover the pool
  • Ensure that the cover fits well and doesn’t have gaps/rips where debris can enter.
  • Continue to check on the pool throughout the winter. Add the necessary chemicals by pulling back the cover along sides.
  • Make sure you leave some slack on the pool to make way for unpredictable changes in water levels.


Your pool is now all set ready for winter! Enjoy a smooth and hassle free spring opening of your pool. If you have any questions or if you’re unsure about any of the process involved in closing your pool, text us at 415-299-8082 and we’ll let you know what to do.

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