10 Tips To Winterize A Swimming Pool

A LOOP LOC winter swimming pool cover.

Closing or winterizing a salt water pool is the same as a chlorine pool in terms of what needs to be done. If you live in a winter climate like I do, there are a few extra steps involved to ensure that pipes don’t crack and get damaged when the temperature drops below 0.

NOTE: The first several years we owned the pool, I paid our pool company to open and close the pool but after watching what they did each year, my wife and I started doing it ourselves.

When you do it right, you not only get a sense of achievement and learn more about how your pool works, but you’ll probably save $300 in closing costs or more that a pool company will normally charge.

Here are tips to winterize an inground swimming pool along with some commentary on my personal experience with the process each year including how to minimize if not eliminate the chance you get algae over the winter.

It's important to clean and vacuum your pool before closing.
It’s important to clean and vacuum your pool before closing.

Tips To Winterize A Swimming Pool

Don’t close your pool too early

I learned this the hard way. Labor Day hits, the temperatures started dropping, kids are back at school and the pool isn’t being used. So I’d call the pool company and by mid September our pool was closed. Then the following May when I took the pool cover off to take a look prior to reopening the pool for the summer, I’d be staring at pea soup.

The water was full of algae.

Try if possible not to close your pool until as late as possible when the temperatures have dropped and you’re no longer getting super hot sunny days. The longer you can wait, the less chance algae has a chance to grow.

Guideline: When the temperature drops and stays below 65°F or 18°C, that’s a good time to close it.

One week before closing, start the process

Ensure the water chemistry is balanced and adjust if necessary. That way you have 1 week to get the chemistry correct. Start by adding a bottle of phosphate remover into the pool to prevent against the aforementioned algae growth. This can help too if you or your neighbors are using fertilizers (they have phosphates, nitrogen, etc) which can get into the pool and mess things up.

We had a bad phosphate problem one summer and it took me a week to figure out what it was and another week to get rid of it with chemicals.

You might take a water sample to your pool company at this point or test it yourself to ensure the numbers are close. I find with the salt water system, the numbers are pretty much spot on the whole summer.

Day of closing, brush and vacuum the pool

Brushing the pool gets rid of any stains and dirt that has accumulated. Vacuuming the pool gets it nice and clean so it’s ready to go in the spring when you’re ready to reopen it.

Leaves and twigs that sit in the water over winter disintegrate, make a mess that is harder to clean up and get slimy. The more colorful leaves might stain the pool liner (I had it happen).

Adjust the water level

Freezing area: If you live in a freezing zone like I do, our pool company always pumped pool water out and kept pumping until it was a few inches below the intakes on the side of the pool. The kept our pool pump running until the lines were flushed clear and then shut it off. I do the same now that I handle the closings.

Non-freezing area: From what I’ve been told and what I’ve read, those of you who live in a non-freezing area will actually add water to your pool and try to get the level as close to the top as possible. You’re not worried about freezing water over the winter so it’s not a big deal like it is for those of us in colder environs!

Water level needs to be dropped below the water return jets to flush water out for the winter if you live in a winter freezing zone.
Water level needs to be dropped below the return jets to flush water out for the winter if you live in a winter freezing zone. They are then capped and screwed tightly to prevent snow water from coming in.

Shock the pool

This is one of the best tips to winterize a swimming pool. It was always missed by our first pool company and we ended up with pea soup every spring as a result: Green water that took me a week and many chemicals to clean up come spring time.

It wasn’t until we switched pool companies that I saw them dumping a container of liquid chlorine into the pool on the day of closing after they’d drained the water that I realized the importance. I asked the new pool company why they did this and this is what they told me.

Shocking the pool improves the chances that bacteria can’t grow and produce algae over the winter and for some reason, our first pool company skipped it every single time. When the new company shocked the pool upon closing, it really helped and the water was reasonably clear in the spring, for once.

Ideally, you will shock the pool at least the night before closing or maybe 2-3 days prior so it can properly circulate throughout the pool and kill bacteria.

Store pool parts inside

Once the water has been pumped out, you can shut the pump down and take things apart. Take the skimmer basket, hoses, chlorinator cell and pump parts and store them inside where it’s safe. I never left any of this stuff outside over the winter. I also took the pressure gauge from the filter and brought it inside too to keep it safe from freezing temperatures. More on that below.

You may want to cover your chlorinator system, pool heater, pool pump, filter, etc with a tarp or some other protective device if it’s in the open and not in a shed.

Take care of the filter

We have a Sta-Rite System 3 cartridge filter. Once the pump has been shut off for the last time, we open the pressure valve to release the pressure and then take the gauge off to be stored inside the garage for the winter. We then take the brackets off the sides of the filter housing and take them inside for the winter. We also unscrew the drain off the bottom of the filter and take the cap inside for the winter. That way if water gets inside it will drain out and won’t build up in the filter.

If you have a filter that requires backwashing, you’ll want to follow recommended instructions which often involves backwashing and cleaning the filter as per manufacturer instructions.

Drain everything (for freezing temperatures)

You’ve already drained the return jets. Now we open everything that we can to drain any remaining water. Our Hayward SuperPump has a small valve that can be unscrewed to drain water. The skimmer is taken apart and the skimmer tray is stored inside for the winter. I put the skimmer top back on again to keep water out. We also drain the pool heater and shut the gas line off for the winter.

We then cap the water return jets (we have 2) tightly with a plastic plug that screws in, so that when it snows and the water level rises, the water stays out of the pipes. We also cap the skimmer intake with a special green plug that we own called a Gizzmo. It screws into the skimmer hole and is designed to absorb the expansion associated with frozen water that gets into the skimmer during harsh winters and may freeze.

Winter cover is applied over the pool

We own a green mesh LOOP-LOC pool cover that is attached to the interlocking bricks around the side of the pool. It’s then pulled tight so it covers the entire pool and basically looks like a trampoline cover. It keeps things safe so no one can fall in the water, but also keeps leaves, etc out over the winter. Snow can sit on top of it but water melts through the mesh if needed.

You may have heard of LOOP-LOC. They did a famous commercial years ago to prove the strength of their covers when they had an African elephant named Bubbles walk across a pool with the LOOP-LOC securely fastened over top of it. So if you have a dog or kids, it might be worth looking at for the safety aspect alone.

In our experience, the amount of snow we get always brings the pool water up either just below what we need or a little bit too much. I’ve never had the pool overflow over winter.

Other suggestions

If you live in a freezing zone area, you might consider pouring antifreeze into the skimmer once everything is capped to fill the pipes. That way water won’t leak in and if it does they won’t freeze. Some people don’t like the addition of another chemical into the pool. Our first pool company didn’t use it but our second company did.

You may also want to take the ladder out of the pool if it’s removeable. I take the ladder out and leave it in the garage. If you have a slide, there may be a winterizing aspect too since it normally has a water line.

You may also pour an algaecide in the pool especially if you are closing it earlier than you’d like.


There are a few extra steps for closing an inground pool if you live in an area that gets snow and where the temperatures get to freezing level over winter. The last thing you want is to leave water in the pipes and get cracks or more severe and costly damage over winter.

The first few years we owned a pool we let the pool company close it each year but we learned how to do it ourselves and now save money on the process.

One of the most important tips I’ve learned is to not close the pool too early and run the risk of algae when the pump is off and the weather is still warm.

I also learned about how shocking the pool with chlorine a day or so before closing can help to decrease the chance of algae building up over winter. Don’t end up with pea green pool water in the spring like I did when our first pool company neglected to do this.

Carl Mueller

I bought a home with a salt water pool in 2006 and soon realized the benefits over traditional chlorinated pools. On this website I'll discuss all the tips and tricks I've learned over the years. I'll also help you troubleshoot various problems with pools in general and ones specific to salt water pools that I've experienced personally!

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