How to Close And Winterize a Swimming Pool

The Definitive Guide On How-To Properly Close And Winterize a Swimming Pool – Detailed Instructions For Closing In-Ground And Above Ground Pools

Pool closing time is usually a sad time of year. The weather is getting cold, the leaves are changing color and the warm memories of summertime fun are fading away.  This is not usually the time of year that people like to think about their swimming pools, but this is really the most important time of the year to pay attention to the pool to avoid unnecessary problems and costly repairs come Springtime.

The following are generalized instructions on how to properly close an Inground and an Above Ground pool.  Please note that all pools are somewhat different and your pool may need specific care not mentioned here.  If you have any doubts about how to properly close your particular pool, either give us a call or contact a local pool professional.  Remember…better safe than sorry!

How To Close A Pool

How To Close An Inground Pool Video Complete swimming pool closing instructions.

Inground Pool Closing (Winterizing)

Step #1

Locate all your winterizing supplies.  This should include the cover, the water tubes, the plugs for the skimmers (gizzmos) and return jets and your winterizing chemicals.  You will also need an air compressor or a powerful shop vac.  You need these items for proper winterization. If you are using the green Gizzmos to plug your skimmers, check them out and make sure that they are not cracked.   This is very important when dealing with gizzmos. Gizzmos with holes or cracks will not work !

Step #2

Backwash the filter very well to clean it out.   Drain DE filter tanks and leave backwash valve open.  On sand filters, unplug the filter drain plug and leave off. Put drain plug with other removed items in the pump basket. Make sure multiport valve has no water in it. Blow it out with a compressor or shop vac if necessary. Please note that it is not recommended to “acid wash” DE filters at the time of the pool closing.  This is best to do in the Spring so that you can immediately run pool water through the system.  It is not good to use muriatic acid on a DE filter and then just rinse it off and put it away.  The acid may degrade the filter parts over the winter.

Step #3

Disconnect your pump and filter.  Make sure that pump is totally drained out of any water. Turn pump upside down once to make sure !   Remove any drain plugs from the pump.  It is a good idea to store any small plugs or parts in the pump basket.  This way you will be able to find them easily in the Spring.

Step #4

If there is a heater, drain it and make sure there is no sitting water inside.  Blow it out with a compressor or shop vac. Drain heater totally and remove all drain plugs (if any). Put drain plugs in the pump basket for safe keeping.  We do not recommend to remove the heater tray.  You can remove it if you want, but you may have trouble putting it back in the Spring.  It is not necessary on most units.

Step #5

Unscrew and loosen any quick disconnect fittings or unions at your pump and filter system.  Remember, the name of the game is “no freeze cracks”.  If the water is all drained out of your pipes and fittings, it cannot freeze and expand and crack.

Step #6

Remove all return jet fittings ( the entire fitting ! ). If you crack a fitting while removing it, don’t panic!! You can get a replacement come Spring.  Remove all skimmer baskets. Put fittings and any other items that you remove in one of the skimmer baskets or the pump basket to avoid loss ( this includes the dive board bolts too ).

Step #7

Blow out all return jet pipes using an air compressor or shop vac. Hook up air compressor or shop vac to the return lines at the filter system – or – some people prefer to screw the compressor fitting into the drain plug of the pump.   This will give a good seal and allow you to blow out the entire system from that one spot – but this is up to you.  Keep the air blowing until the air bubbles start to become visible from the return jets in the pool.   Put a plug in the fitting under the water when you see the bubbles blowing at full force. This will mean that 99% of the water is out of the pipe.  Make sure plug is in tight ! This is most important.

Step #8

Blow out all skimmer (suction side) pipes in a similar fashion as noted in #7. Put a Gizzmo-type screw in plug in the skimmer when bubbles start to become visible. We know that this is sometimes difficult, but proper gizzmo installation is important. Make sure that you put PTFE tape on the gizzmo threads before installing. This insures a tight seal. If you don not want to use Gizzmo plugs and want to use black rubber-type plugs instead, that is OK as long as there is something in the skimmer to allow for water expansion when it freezes. Usually a closed plastic empty soda-type bottle will work. This is very important !  Do not just plug the skimmer lines and forget about them.  Water can easily freeze in a skimmer and crack the plastic.  This would be bad ! 

Step #9

Also, if you have a slide, an auto vac system or a waterfall, you will have to drain and blow out those pipes as well. Remember – we do not recommend putting anti-freeze type products in the pipes.  You will not need it if the lines are properly blown out.  The anti-freeze can cause a mess in the Spring when you go to start your system and it gets sucked into your filter and blown back into the pool.  Try to avoid antifreeze – if possible – by properly evacuating all the water from the pipes.

Step #10

Blow out main drain line (if any). No, you don’t have to dive down and plug the drain pipe. When you see bubbles coming out of the drain, plug the pipe on your end or close the gate valve. This is as much protection as you can give to a main drain line.  By doing this you will cause an “air lock” in the line and no more water should enter the pipe from the pool side.

Step #11

Put duct tape on all exposed pipes to prevent anything from getting into them. Use a lot of tape, it’s cheap !

Step #12

Remove rope and floats from pool and put with the rest of the supplies.

Step #13

Remove dive board and ladders. Put in a safe spot – a shed or the garage.  Put the pump and filter in the shed or garage as well.  You probably are not going to want to move your filter if it is a sand filter.  You can leave that outside !  Remember … do not lose dive bolts or ladder bumpers. Put them in the skimmer or pump baskets.

Step #14

Mix any granular winterizing chemicals in a bucket so that they are totally dissolved. Dump mixture into the pool. You want to avoid any undissolved granules from settling on the pool floor and staining the liner. This is very important. If you are using any liquid winterizing chemicals, pour them in the pool as well.  Test the pool for pH and Total Alkalinity.  Adjust to normal levels using pH PLUS or MINUS and ALKALINITY PLUS.  pH should be between 7.2 – 7.6 and Alkalinity between 100-150 ppm.  Make sure one of your winterizer chemicals consists of a SHOCK-type product.  You want the chlorine level in the pool to be rather high (over 3.0 for wintertime).

Step #15

Water level.  This is an area of a little controversy with some people, so we are going to tell you how they close the pools in New York & the Northeast.  You do not have to drain any water out of the pool provided that you have properly blown out and plugged all your underground pipes as outlined above and you do not have a pool that has decorative ceramic tiles at the water line.  Some people are used to their pool being drained down past the skimmer. This is usually done instead of blowing out the pipes and using gizzmos. Realize that the higher their water level is through the winter, the better it is for the pool cover. Pools that are drained down low cause a lot of undue stress on the pool cover thereby shortening its life – as well as exposing the pool liner to the air and causing it to prematurely dry out.

The use of gizzmos prevents the skimmers from cracking, plugs the pipes and allows the water level to remain high for the cover so that rain water does not cause a lake on top of the pool cover – possibly causing it to fall in. We feel that the way we have stated to close a pool is the proper way.  You really only have to drain the water down in a pool if it has tile at the water level because the surface water will freeze and expand over the winter and this could cause those tiles to crack.  Aside from this situation, we feel that there is no valid reason to lower the water in the pool.  Also, you do not have to remove or “lower” the pool light provided that you keep your water at the normal level.

Step #16

Place the cover on the pool. If there are rips or tears in the cover that are repairable, patch them with either vinyl pool patch (for vinyl covers) or with pool cover patch tape ( for lightweight covers) or with a heavy duty duct-type tape. Remember, if your cover was declared legally dead a few years ago then patching probably is not the right thing to do !  It is probably time to get a new cover.  If there are sharp points that extend into the pool, like step units or “ELS”, then it is a good idea to put rags or cardboard between the cover and the points on the pool which extend out.  Do this right or the cover may rip on those stress points.

Step #17

If you use water tubes, lay out the water tubes, placing them through loops on cover. Fill tubes with water to approx. 85% and tightly seal all tubes. Do not overfill the tubes – when they freeze you do not want them to expand and split.  Tubes should ideally be touching each other end to end. However spacing them one (1) foot apart is OK. If you find that tubes are leaking do not fill them. Replace them with new.  It is not a good idea to patch the old tubes unless you absolutely have to.  Remember…do not overfill tubes. They should not be totally filled with water. Allow enough slack in the tube for water expansion !

Above Ground Pool Closing ( Winterizing )

Step #1

Locate all your winterizing supplies.  This should include the cover, the air pillow, the plugs for the skimmers ( gizzmos or rubber plugs ), the winter plate ( if used ) and your winterizing chemicals.  You need these items for proper winterization. If you are using the green Gizzmos to plug your skimmers, check them out and make sure that they are not cracked.  This is very important when dealing with gizzmos. Gizzmos with holes or cracks will not work !

Step #2

Backwash the filter very well to clean it out.   Drain DE filter tanks and leave backwash valve open.  On sand filters, unplug the filter drain plug and leave off. Put drain plug with other removed items in the pump basket. Make sure multiport valve ( if any ) has no water in it. Blow it out with a compressor or shop vac if necessary. Please note that it is not recommended to “acid wash” DE filters at the time of the pool closing.  This is best to do in the Spring so that you can immediately run pool water through the system.  It is not good to use muriatic acid on a DE filter and then just rinse it off and put it away.  The acid may degrade the filter parts over the winter.

Step #3

Plug return pipes and skimmer (see #5 for skimmer details  and remove all hoses.

Step #4

Disconnect your pump and filter.  Make sure that pump is totally drained out of any water. Turn pump upside down once to make sure !   Remove any drain plugs from the pump.  It is a good idea to store any small plugs or parts in the pump basket.  This way you will be able to find them easily in the Spring.   Store in a shed or garage.

Step #5

Some people like to remove the skimmer box and install a winter plate with gaskets.  If you do this, make sure it does not leak.  Yes, you will get wet doing this !  Most people simply plug the skimmer hole with a black rubber plug or a gizzmo.  It is easier.  You can let the water in the pool go down to the bottom of the skimmer if you like – then you do not have to plug the hole at all.  This method is also OK, but realize that the pool cover will sit lower in the pool – therefore you might want to use a cover that is one or two sizes bigger than your pool so that you have the extra material available.  Any of these methods are OK – it is mainly personal preference.

Step #6

Blow up and install your air pillow.  Air pillows are usually used but are not absolutely necessary.  They are a good idea in case the water in the pool freezes, expands, and breaks the pool wall. The pillow takes up the slack.  However realize that this is somewhat rare. If no pillow is available, you can use tires, tubes, balls, or other air filled floating objects.  Throw them into the pool to take up ice expansion. Tie air pillow at two places and position in center of pool. Tie strings to the pool wall so the pillow does not move during cover installation. If the pillow is leaking, either patch it or get a new one. Remember…the pillow is there to take up any expansion of the water which may occur due to freezing and possibly causing the above ground pool wall to split.  Pillows are NOT to keep the rain water out of the pool cover.  They will not do that.  The rain water will always settle around the outside of the pillow.

Step #7

Remove all deck equipment from pool, if any (ladders, rails, slides, etc.).

Step #8

Add chemicals. Mix any granular winterizing chemicals in a bucket so that they are totally dissolved. Dump mixture into the pool. You want to avoid any undissolved granules from settling on the pool floor and staining the liner. This is very important. If you are using any liquid winterizing chemicals, pour them in the pool as well.  Test the pool for pH and Total Alkalinity.  Adjust to normal levels using pH PLUS or MINUS and ALKALINITY PLUS.  pH should be between 7.2 – 7.6 and Alkalinity between 100-150 ppm.  Make sure one of your winterizer chemicals consists of a SHOCK-type product.  You want the chlorine level in the pool to be rather high (over 3.0 for wintertime).

Step #9

Place cover on pool and secure. Make sure that cover cable wire is tight so that cover does not blow off or fall in pool. Make sure the pillow is still in the middle of the pool after cover installation. If not, reset cover and pillow.

Commonly Asked Questions about Pool Closings (Winterizing )

What kind of chemicals do you put in the pool ?

We suggest a the use of a concentrated shock treatment along with a winter algaecide and stain treat product.  Also make sure you adjust the pH and Alkalinity of the water.

Do you put any Anti-Freeze in the pipes ?

No…you should not have to. The only way that you can guarantee that your underground pipes don’t freeze is to blow all the water out of the pipes with a high powered air compressor or shop vac. The only time you would need to add Anti-Freeze is if you were going to leave water in the pipes. Then you would have to add it to keep them from freezing – but this is not recommended.

Do you drop the light – lower the light – remove the light ?

No…you do not have to lower the light. A long time ago, before people used compressors or shop vacs to blow all the water out of the pipes, they had to lower the water in the pool down past the returns. Then they used to have to remove the light and drop it to the bottom of the pool because if the pool water froze, it might expand and actually crack the light. Now a days, since you can use the compressor to blow out the pipes, you can keep the water level in the pool high up…so your light can stay where it is. There is much less of a chance that the light will develop a leak if you just leave it alone.

Why do you have to lower the water in the pool if the pool has tile around the top at the water level ?

If you have tile, and you do not lower the water level, then if the water freezes, it can expand outwards and actually crack the tile.

Do you have to lower the water in a vinyl liner Inground pool ?

The only time that a pool needs to have the water lowered is if you have a gunite or cement pool with tile around the top, you know, at the water line. If you have tile, and you do not lower the water level, then if the water freezes, it can expand outwards and actually crack the tile. That’s the only reason. If you have a liner in the pool, then there is no need to lower the water level. When you use high powered compressors to blow all the water out of the pipes, and plug the return jets and the skimmers there is no need to lower the water. As long as you have the GIZZMOS, those big green plugs for the skimmers, you can keep the water at the regular level. The higher you can keep the water in the pool, the better it is for your pool cover and there will be much less of a chance of the cover falling in.

Well, I would prefer that the water be lowered.

Basically it’s your pool…and if you are more comfortable lowering the water level, then by all means do it. However you should still follow the procedures listed above for blowing out the pipes as well.

Should I acid wash my DE filter before closing ?

You should backwash it out before you close it down. That gets all the “gook” and old DE out of the filter. If you want to have the filter “acid washed”, that’s usually something you do at the pool opening. You don’t want to have the filter cleaned and then have it sit for the next six months with acid residue in it ! Most people want to have it cleaned out right before they start up the pool in the spring. It is best to wait till then.

Well, I really want it cleaned out now – I heard from a friend this was best.

Well, the problem is, to properly clean it out you should use muriatic acid. And after the filter is cleaned out with that stuff, you are supposed to re-attach it to your system and immediately start running pool water through it. If you acid wash it and just put it away, you could really damage the insides of the filter, even if you hose it off really good. The filter manufacturers do not recommend to acid wash a filter if you are going to close it right away. It is really best to do it in the spring.

Should I vacuum the pool before I close it ?

Well, this is up to you. We do not recommend closing the pool if there is A LOT of debris in it.  Then you should vacuum it all out.  But a few leaves and bugs are OK.  Most people vacuum the pool right after they open it in the Spring. You know, if we have a bad winter and part of your cover falls in the pool, you’ll just have to vacuum it again when you open it, so most people would rather just do it in the spring and only have to do it once.

Winter Pool Care Instructions

Now that your pool has been properly closed, please do not totally forget about it! With a minimum of care and maintenance throughout the winter months, your cover will last longer and your pool will open up with less problems in the spring. Follow the instructions below for best results.

Above Ground Pools

Periodically check your cover cable to make sure that it is tight. If the cable becomes loose, the cover might start to slip into the pool. Check your air pillow to make sure that it still has air in it. If you see it starting to go flat, get another one and slip it under the cover and blow it up. Remember, the air pillow is not in the pool to keep rain water off the cover ! It is there to keep your pool walls from splitting if the water in the pool freezes and expands. It does not matter if the pillow is in the center of the pool and it does not matter if it is not 100 % inflated.

Pump (or siphon) the rain water off the cover a few times throughout the winter. Also remove any leaf accumulation that may occur on the cover. Excess water and leaf weight can cause undue stress on the cover and could cause the cover to rip or fall in. Check the water level in the pool every month. A slow leak in the liner could cause you to lose a lot of water from the pool. If you notice the water level dropping, simply refill with a hose and keep it as high as possible to prevent damage to the cover, liner and walls.

If you notice part of the cover falling into the pool, pull it up and properly reset it right away to prevent damage.

Inground Pools with Water Tube Type Covers

Make sure you replace any water tubes that break over the winter. It is a good idea to have a few extra tubes handy so that you can replace them as needed. Remember, the tubes not only hold the cover on the pool, but also prevent wind from blowing the cover up. Any areas that are not properly covered with tubes could cause the cover to fall in or blow up. Do not use cinder blocks, bricks, flower pots, lawn furniture or other heavy items to keep your cover in place.

If the cover starts to fall into the pool, it could drag any of those objects into the pool causing massive damage to the pool cover and/or liner. Pump the rain water off the cover a few times throughout the winter. Also remove any leaf accumulation that may occur on the cover. Excess water and leaf weight can cause undue stress on the cover and could cause the cover to rip or fall in. Check the water level in the pool every month.

A slow leak in the liner could cause you to lose a lot of water from the pool. If you notice the water level dropping, simply refill with a hose and keep it as high as possible to prevent damage to the cover, liner and walls. If you notice part of the cover falling into the pool, pull it up and properly reset it right away to prevent damage.

“Loop Loc” Mesh – Spring Type Covers

Tightness: The springs and straps on your cover will need to be adjusted from time to time, especially during the first few seasons of use. The cover material, as well as the straps, will start to stretch as soon as the cover is initially installed. THIS IS NORMAL. Check cover periodically over the first few seasons of use, and retighten the straps as necessary.

Water Level: The water level in your pool should be kept at or just below the skimmer when the cover is in use. However, the water level should not be lower than 18″ from the top of the pool. If your water level goes down further than 18″, the cover could stretch out too much and either rip or cause anchors to pull out of your deck. If you experience a lot of precipitation over the winter months when the cover is in use, it is possible that the pool could fill up, no longer allowing the water from the cover to drain into the pool. Check pool water level periodically over the winter, adding or removing water when necessary with your garden hose or cover pump.

Water Clarity: Remember, this is a mesh pool cover. Sunlight and rain water will get through the cover to the pool water. Most pools covered with this type of cover will remain clear until April or May, depending on the weather. It is strongly recommended that you open your pool early to avoid the green “swampy” water that occurs when strong sunlight and temperatures over 80 degrees are present. As a rule of thumb, you should open your pool prior to May 15 to avoid a green water situation. It is also a good idea to add 2 or 3 gallons of chlorine shock to the pool in the beginning of April to ensure good water clarity at opening time.

“Solid” – Spring Type Winter Covers

Tightness: The springs and straps on your cover will need to be adjusted from time to time, especially during the first few seasons of use. The cover material, as well as the straps, will start to stretch as soon as the cover is initially installed. THIS IS NORMAL. Check cover periodically over the first few seasons of use, and retighten the straps as necessary.

Water Level: The water level in your pool should be kept at or just below the skimmer when the cover is in use. The water level should not be lower than 18″ from the top of the pool. If your water level goes down further than 18″, the cover could stretch out too much and either rip or cause anchors to pull out of your deck. For most manufacturers of Solid Spring type pool covers, this could void your warranty ! If you experience a lot of precipitation over the winter months when the cover is in use, it is possible that the pool could fill up, no longer allowing the water from the cover to drain into the pool. Check pool water level periodically over the winter, adding or removing water when necessary with your garden hose or cover pump.

Cover Draining: Although the mesh center drain panels of your cover will allow rain water to drain into your pool, they are not designed to drain off every drop of water from your cover. Because of the way that the cover straps are situated, some water will puddle in areas of your cover. THIS IS NORMAL AND THERE IS NO WAY TO STOP THIS FROM HAPPENING. Do not try to over – tighten the cover straps in an attempt to get all the cover water to drain into the mesh panels. It will not work, and you run the risk of over – stretching the straps and springs. For most manufacturers of Solid Spring type pool covers, this could void your warranty ! The center mesh drain panels are primarily designed to let most of the water drain off the cover.

Mesh Panel: To ensure proper drainage, make certain the mesh center drain panels are clear of leaves and debris. Check cover periodically over the winter and remove debris from panels as it accumulates using a pool leaf net, vacuum pole or broom. This is especially important for pools located in heavily wooded or treed areas. If you walk on the cover to get to the panels, make sure you are not wearing shoes with spikes or heels, as this could puncture the cover. Failure to keep the mesh panel free from leaves and debris will result in improper water drainage from the surface of the pool cover and will cause too much water weight on the pool cover. This could cause the cover material, straps and/or hardware to stretch or break. For most manufacturers of Solid Spring type pool covers, this could void your warranty !

Water Clarity: Remember, this cover has mesh drainage panels. Some sunlight and rain water will get through the cover to the pool water. Most pools covered with this type of cover will remain clear until April or May, depending on the weather. It is strongly recommended that you open your pool early to avoid the green “swampy” water that occurs when strong sunlight and temperatures over 80 degrees are present. As a rule of thumb, you should open your pool prior to May 15 to avoid a green water situation. It is also a good idea to add 2 or 3 gallons of chlorine shock to the pool in the beginning of April to ensure good water clarity at opening time.