Closing Pool for Winter - Further Reading

How to Close a Pool for the Winter

How to Close an Above Ground Pool

Closing your Above Ground Pool in TFP Pool School.

How to Close an In-Ground Pool

Closing Your In-Ground Pool in TFP Pool School.

The concept of closing an in ground swimming pool

Blowing out main drain?

Winterizing Paramount's In-Floor Cleaning System.

How To Use Polyquat 60 in Pool Winterization

How To Use Polyquat 60 in Pool Winterization?

Connecting Air Through Pump

Modified Pump Cover to Connect Blower for Closing Swimming Pool

Modified Pump Lid

A modified pool pump cover can be used to connect the air output from a blower to the plumbing. These modified covers are custom made.

Few tips when making your modified cover:[1]

  • Go very slow or you will bind up.
  • Clamp it down or it will go for a spin.
  • If you order a new lid, use it for the pump and use old one for the modifications.
  • Do not not use silicone unless absolutely necessary. The fittings that go thru the lid will have rubber gaskets that would seal it.
  • Make sure you get the correct 6' hose.

Modified Cover for Hayward Super Pump for Closing Swimming Pool gives more details on the process.

Connecting Compressor to Pump Using Drain Port

Pump Drain Port Air Connection.jpg

A compressor can be connected to the 1/4” npt drain port of the pump to blow air into the suction and return lines.

You can then isolate the suction and return side with winter plugs. Plug the return side and work on the suction side. Then plug the suction side and work on the return side.[2]

Remove the lid and inside you will have the ports where the plumbing is attached, both suction and the return side. The suction (Main Drain and Skimmers are toward the shut off valve). The back is the return side. The plugs that will fit are either #8, #9, #10 or # 11. Plug the port inside the housing. Only plug the side you want air NOT to travel.

Or you can use the shut off valves to close off the air traveling towards the skimmers & main drain, but the winter plugs work best. No need to over tighten either, just snug as they are not going anywhere.

How Much Air is Required to Blow Out Lines?

Low pressure and high volume is best to blowing air through the lines. You only need 3.5 psi to clear a pipe 8 ft below water level.

Bursting due to air pressure is a non-issue. Typical 2" plumbing has a bursting pressure of 890 psi. Glue joints, if done properly should be just as strong if not stronger than the pipe itself because of the double thickness of the pipe wall at the joint.[3]

Techniques to Air Lock the Main Drain

Winterizing the main drain, if you have one, depends on the way the main drain is plumbed into your system. You do not, and cannot, clear the main drain of water. What you want to do is clear the water down the pipe until close to or at the frost level. That gives a free column for any water and ice to expand into.


If your main drain has its own valve it should be air locked with the shut off valve and then the air compressor immediately shut off.

First shut off the main drain to clear skimmers. When done, close skimmers with valve and clear main drain. After bubbling, shut off main drain and then shut off the compressor to not create back pressure.

Foam Rope

If the main drain is connected to a hole in a skimmer you can push a 4’ piece of foam rope into the hole and be done with it.[4] It takes patience and good fingers to push against the water pressure. Then plug the hole with the foam rope in. Hold the plug down with your pinky while using thumb and index to push the rope in.

Winterizing the Skimmer

Once the skimmer lines are blown out the objective is to displace water from the skimmer so that if ice forms in it the ice has room to expand up. Ice does not expand more than 9% and will go upward in the skimmer.[5]

People fill the skimmer with one or more of the methods below.


Gizzmo for skimmer.jpg

There are various size Gizzmos for in-ground and above ground pool skimmers. The Gizmo screws into the skimmer line. There are many products similar to the Gizzmo for absorbing the expansion of ice in the skimmer.

The Gizzmo needs teflon tape on the threads to seal well.

Some Gizzmos have a a blowout valve on the top in the top to blow out lines. If you have a Gizzmo that has an opening at the top and air is coming out of the threaded area, then the threads on the Gizmo may be stripped.

Pool Noodles

  • pool noodles are made from closed cell foam which doesn't absorb water.
  • put 6" of "pool noodle" in the skimmer, just in case rain, snow, etc fills the pool back up
  • Cut a 8 inch piece off the end of a noodle. Place it in skimmer.[6]
  • If you use pieces of pool noodles along with the Gizzmo's, wrap them around the Gizzmo in a circular fashion. The more you cover, the less water, which means more protection.

Plastic Bottles

  • one liter plastic bottle filled up half way with antifreeze is fine
  • drop into the skimmers a plastic water bottle filled half way with windshield washer fluid.
  • use a gallon jug of Antifreeze with about 1/4 left in the jug. It fits in a skimmer perfect, and add a little antifreeze to the skimmer box

Winterization Plugs

Winterizing plugs are used to seal the return and skimmer holes. They can also be used to plug the pump intake and outlet and individual lines during the blowout process.

Rubber Expansion Plugs

Rubber Expansion plug.jpg

Tapered rubber winter expansion plugs with a wingnut to tighten come in various sized:

  • 0 - 1/2" pipe tapered
  • 1 - 1/2" pipe
  • 2 - 3/4" tube tapered
  • 3 - 3/4" pipe
  • 4 - 3/4" and 1" pipe
  • 5 - 1" pipe
  • 6 - 1" fitting
  • 7 - 1 1/4" pipe tapered
  • 8 - 1 1/2" pipe tapered
  • 9 - 1 1/2" pipe and 1 1/4" fitting tapered
  • 10 - 1 1/2" fitting tapered
  • 11 - 2" pipe
  • 15 - 4" pipe
  • 16 - 4" pipe

There are also extra long tapered plugs that can cover #7 to #10 sizes.

Blow-Thru Valve Winter Pool Plugs

Winter Plug with Blow-Thru Valve.jpg

Blow-Thru Valve Winter Pool Plugs are tapered rubber plugs with a Schrader valve stem.

Most members with an air compressor usually connect an NPT fitting to the pump basket, then clear the lines with an air compressor, or they create some adapter and work from the skimmers, unions, etc. If you are working on the return side, this would mean that you will have to isolate the suction side to create enough air volume to accomplish the task and vice versa.[7]

With the blow thru plugs, one can simply place in a the pump basket housing, and use an air compressor to move water with air. This method would only require 2 plugs and an air compressor (One on the return side and one on the suction side)

They are also useful for blowing out pipes, such as a main drain, where you don’t have a valve.

Threaded Return Line Plugs

Hayward SP1022C plug.jpg

A threaded plug with an O ring will screw into return lines to seal them for the winter. It is the Hayward SP1022C 1.5" MPT Plug with O-Ring, White with similar plugs from other manufacturers.

The threaded plugs fit 1 1/2" return fittings. The Hayward SP1419T seat removal tool will remove the directional fitting to plug it during winterization.

Use Teflon tape on the threads and Pool Lube on the O ring.

This 1 1/2" threaded plug can also replace the drain plug in XtremepowerUS, Hayward and Pentair filter tanks