How To Close An Inground Pool

Learning how to close a pool is much easier than most people might think.  And properly closing your pool will make your next pool opening much easier.  You'll already have a head-start and you'll use less chemicals.  It takes a little extra effort to close your pool the right way but it's an investment that pays off big time come next Spring.  Of course, when in doubt, it's best to hire a great pool tech to close your pool for you. 

Why You Should Close Your Pool 

Thousands of pool owners just like you ask that question every year, and for good reason.  There are certainly benefits and drawbacks to keeping your pool open or closing it.

Ultimately, closing your pool is a personal choice, but it should be dictated by reason and, of course, your climate and environment.  What one pool owner chooses to do might not be in your best interest.

Let's think about this for a second.  Remember the work that went into taking care of your pool during the summer?  Now let's think about the same level of service, only this time it's cold, windy, and maybe snowing.  Do we really want to be slushing around in that?  Not to mention your beautiful pump motor being cold, pipes freezing, and let's not forget your filter that turned into a "filteriscle".   

When Should You Close Your Pool? 

One again, this is debatable.  I've known people who close their pools right after Labor Day, even when daytime temperatures can reach into the high 80s or low 90s.  If we cover our pools when it's still that warm, our pools will turn into the perfect environment for a massive dose of algae when we get to pool opening season.  When to winterize your pool might just as important as how to winterize your pool.

A good rule-of-thumb is to wait as late as you can.  This means the temperatures should be no higher than 60°F (15°C).  Temperatures below this point makes it very difficult for algae and bacteria to grow and reproduce. 

If your temperatures are consistently over 60°F, you can simply maintain your pool as you would during the swimming season, then close your pool when the time comes. 

What You Need To Close Your Pool 

You may already have many of the supplies you need to winterize your pool.  What you need and how much will depend largely on the type and size of pool you have, your environment and surroundings, and if the pool was maintained through the summer. 

• Air compressor
• Test kit
• Algaecide
• Chlorine
• Metal sequestrant
• Pool brush
• Vacuum
• Telescopic pole
• pH decreaser such as dry acid
• pH increaser (if applicable)
• Calcium hardness increaser (if applicable)
• Alkalinity increaser (if applicable)
• Skimmer Gizzmo or skimmer plate
• Tools for removing ladders and securing your winter cover
• Winter pool cover

Make sure you go down the list and get everything you need before you start to close your pool.  The last thing we need is to forget something and make an emergency trip to the pool store. 

How To Close Your Inground Pool

The pool winterizing process will be determined by your location and how well you're prepared.  If you live in warmer climates like Arizona or Florida (two states that I lived in) then you probably won't need to close your pool.  Filtering for 4 - 6 hours per day and maintaining your chemicals are normally enough. 

If you live in colder climates, you will want to close your pool.  Proper winterizing your pool and blowing out the lines will ensure your pool will be safe all winter and the lines won't freeze and break. 

1. Clean Your Pool 

This is your first step.  You will want to thoroughly clean, brush, and vacuum your pool.  Make sure you remove as much debris from the pool as you can.  Anything left over will need to be removed in the spring, so it's best to get it down now.

Brush the steps, walls, floor, and behind the ladder.  Brushing will help kick up the debris and dead algae spores into the water and will make your pool shocking process more effective. 

2. Test and Balance The Water

About 3 - 4 days prior to closing your pool for the winter, get your pool pH down to 7.2, pool alkalinity to 80-120 ppm, and calcium hardness to 150-250 ppm.  Properly balancing your pool water will allow the shock to do a better job and reduce the chances of scaling. 

3. Shock Your Pool 

Shocking your pool is a process, not a product you buy.  Add enough liquid chlorine or calcium hypochlorite to reach 15 - 20 ppm.  This will ensure all left-over algae and bacteria are killed.

The normal ratio is to use 1.5 gallons of liquid chlorine or 1.5 packs of calcium hypochlorite.  

4. Add Your Winter Chemicals 

At this point, your chemicals should be balanced.  Now is the time to add the extra chemicals such as a PolyQuat 60 algaecide and a metal sequestrant (if applicable).    

5. Remove Inground Pool Accessories 

Remove the skimmer baskets, slide, any wall fittings, vacuums, pool cleaners, ladders, handrails, or anything else that shouldn't be in the pool.  

6. Lower The Water Level

You can either use your filter pump motor or a submersible pump to lower your pool water level.  This is to prevent the tile from cracking during the hard freezes.  A rule-of-thumb is to lower your pool's water level about 3"- 5" below the skimmer.  This will ensure the skimmer and tile line are safe, while offering support to your winter cover that may experience heavy snow or water weight.   

If you're using your swimming pool pump to drain the pool, be sure to turn your skimmer valve off because your system will suck in air when it's trying to drain.  Turn it back on when blowing out the line.

However, partially draining the pool is an area of debate.  Some may say to not partially drain the pool because it exposes the concrete or vinyl to the air which causes undue stress and premature aging of the liner.  They will say if you properly blow the lines and plumbing out there is no reason to drain some of the water.

Also, some say with concrete (gunite swimming pool) or pools with decorative tiles, you may want to lower the water level below the tile in order to keep it from freezing and cracking.  Check with your local pool store because each part of the country is unique and has different freezing points.

If you have a vinyl liner pool, you can use an Aquador over the mouth of the skimmer which keeps the water out of the skimmer so you can leave the water level up for pool winterization.

7. Backwash and Clean The Filter 

You'll want to do one final brush to winterize your swimming pool.  With your skimmer valve closed, backwash your filter one more time.  If you have a cartridge filter, simply remove it, spray it out and store it for the winter.  

8. Drain Your Filter and Equipment 

Next, you will want to drain your pump pot, filter, heater, and chlorinator or chlorine tab feeder.  Either drain the water out of these or better yet, get your old Shop-Vac and blow the line out.  This will ensure all of the water has drained and none is left inside any plumbing lines.  

For a D.E. pool filter or a cartridge filter, take the grids or cartridge out, clean them, and store them away for the winter.  If the filter housing is small enough, you might be able to take it apart and store it over the winter.

Keep the plugs out of these units.  If you plug them back up and water happens to get into them, they might freeze over and crack your equipment.

Place all the plugs in the skimmer basket during your pool winterization maintenance.  By doing this, you'll know where they are when you need them next spring.  If you have a sand filter, be sure you put the Multi-Port valve in the closed or "winterize" position and remove any pressure gauges.

After you drain the pump pot, turn the pump motor on for second or two to get the water out of the impeller.  If you run the pump any longer, the seal can burn up. 

9. Blow Out The Lines 

You can blow out the plumbing lines for using your Shop-Vac.  Use the discharge of the Shop-Vac to blow water from each plumbing line of the filtration system.  Blowing out the lines will prevent ice from forming in the plumbing.  It also means you won’t need to add antifreeze.

Bubbles will appear in the pool as the water is purged from the lines.  At this point you will need to plug the lines using a threaded plug, if applicable.  Make sure each plug has an O - ring or gasket to give it a tight fit or the water may get back into the line causing all kinds of issues down the road.

Use a skimmer Gizzmo to seal the skimmer throat.  This little guy is a hollow tube that will collapse if the water get into the skimmer and freezes.  Be sure to put some plumbing or Teflon tape around the threads to give it a good seal, and it also makes removal of the Gizzmo a little easier at start-up in the spring.

Be sure to get all the water out of the lines.  Even the smallest pocket of frozen water left inside the plumbing can cause your pipes to burst.

10. Install Your Winter Cover 

Now is the time to break out your winter cover to keep the debris out of the pool.  I recommend using a solid cover that keeps out all debris and sun.  These solid covers should keep the pool clean and reduce algae growth.  I also recommend using an air pillow if a solid safety cover is not being used.  An air pillow hold the pool cover up like a tent so water and debris fall off instead of collecting on the top.  This does work, but not completely.

They also help to take up any water expansion which could occur from freezing and possibly cause your inground pool wall to split.

When In Doubt, Hire A Pro

Well, there you have it.  Closing your inground pool is somewhat time consuming and if not done properly, can turn into a nightmare, not to mention an added expense that you don't need.  This is why I tell people who might be thinking about closing their pools to hire a professional pool service.  Please remember, these pool closing tips and swimming pool winterization guidelines are just that, tips and guidelines.  They are by no means written in gold and I don't assume any responsibility for your inground or above ground pool winterizing.

If you're the least bit unsure of what to do or are not experienced in swimming pool closing or how to winterize a swimming pool, I highly recommend hiring a pool professional.  Good luck.

Can't wait until Summer!!