How to Get the Perfect Chemical Balance for Pool Closing—Fast

Imagine this. You wake up one morning and step outside with a cup of coffee, and you think, huh, it’s pretty warm out. And when you come to think of it, you’ve had mild days for a week or so now—all around 65 or 70 degrees. Wait a minute, you think, it’s time to open your pool! But now imagine that when you do go to remove that pool cover, you instantly regret it—and every decision you’ve ever made. Because that pool? It’s no longer a pool at all. It’s a murky swamp of algae, mold, and who knows what else.

Yeah, we are not going to let that happen. But in order to make sure that your pool’s opening day next year only requires normal, manageable maintenance, your water needs to be balanced the moment you close your pool for the winter season. Here, I’ll explain why it’s important to balance your chemicals, when exactly to do it, and how to get the perfect levels for each of the chemicals your pool needs to stay a swimming pool—and not, you know, a cesspool. Because when it comes to closing your pool, the more accurate your chemical balance is now, the less work you’ll need to do later.

Just Deal With It in the Spring. Right?

Sorry—but as someone who is always trying to save you time and money, I’ve got some news for you. What you do to achieve and maintain chemical balance in your pool while closing it up for the winter is going to go a long way. If you treat it now, and continue to rebalance it intermittently throughout the winter, you’ll only adding a few chemicals every so often. It couldn’t be easier.

But if you’re hands off now and decide to just deal with your pool in the spring, you’ll also have other troubling (and physically strenuous) issues to deal with, such as eradicating algae and mold. If you’re based in an area that reaches freezing temperatures, your untreated water might even lead to permanent damage to your pool and circulation system. That’s going to cost both time and money to fix.

Ready to make the smart decision? Read on.

When it comes to chemical balance, strong circulation is key. My recommendation for above ground pools? Try the Copper Force Above Ground Pool Pump, which has a start capacitor and different horsepower options. According to customer Doug Paar, “The pump is very quiet and has good pressure. I would recommend.”

how to get the perfect chemical balance for pool closing

Okay, I’ll Balance My Pool Chemicals. When Do I Start?

This one’s an easy answer: you’ll want to balance your pool chemicals up to the very second that you’re officially closing your pool, and as part of that process. But it does get trickier than that: you’ll want to give enough time for your sanitizer to circulate before putting on your pool’s winter cover, because part of closing your pool also involves removing your chlorinator, if you have one. And because you’ll be using pool shock during this process, you’ll need to add it to your pool at dusk or at night, and run your circulation system for about eight hours afterward, or however long you usually run your pump per day. After pool shock, we’ll add even more chemicals, but you’ll want your sanitizer to return to its normal levels, which might take a few days. Sheesh.

Seems like a lot, right? Well, if you do it in the sequence I map out below, it should be a breeze. Just make sure that you begin balancing your pool chemicals after cleaning your pool with a pain-free pool brush like the BLACK+DECKER 360-Degree Bristles Pool Brush and using a powerful vaccum like the Blue Torrent MyBoy In Ground Robotic Pool Cleaner. And don’t forget about the next steps of closing your pool after you’ve done this chemical balance.

Now, Let’s Get the Perfect Balance

Step aside, the mythical work/life balance—this is a balance that can actually be achieved to perfection. I recommend adding chemicals one at a time and in this order. Some other pool experts say it’s fine to add them all at once, but it’s also well known that some of these chemicals affect others. Raising your alkalinity, for example, is a sure-fire way to raise your pH. I’d rather do each of these no more than once, but that could just be me.

If you want an even more specific reading of your chemicals, feel free to bring a vial of your water to your local pool authority—once your water is proper balanced. They’ll be able to tell you if you nailed it, and what to change if you didn’t quite get it on the first try. At-home pool test strips are also great.


Like all other chemical levels on this list, your pool’s optimal sanitizing levels for closing are the same as the optimal levels during the pool season. If you’re well-versed in how to add chlorine to your pool, you know that this level is 1-3 parts per million (ppm). If you have a different sanitizer, you’ll have a different number, so make sure you know what the optimal levels are for the right pool sanitizer for you. Any number that is recommended for when the pool is open and full of swimmers—ah, the good days—will be the same number you want to achieve as you are closing your pool.


Like a good, supportive, and always-ready-to-listen friend, alkalinity allows your sanitizer to operate at its very best. Your target range for alkalinity is 80-120 ppm, but make sure that any time you adjust it, you also check in on your pH.

Want both powerful circulation and smaller energy bills? This Blue Torrent 2 HP Variable-Speed Pump is the one to try. Plus, it pays itself off in energy saved in under a year, is eligible for rebates, and comes with a lifetime warranty. As customer Dave Schmidt says, “My pool has never looked cleaner. I am pleased with my new pump!”


If you know anything about pH in pools, you know that it’s a bit of a drama queen. It’s sensitive and needs extra care, but that’s okay—a little maintenance now prevents havoc later. The optimal pH level is between 7.2 and 7.6. If pH allowed to drop too low or rise too high, it can stop your sanitizer from working and destroy your pool walls. And once the pH is just right, it makes swimming enjoyable—which might not matter now, but it’ll matter a whole lot next spring.

how to get the perfect chemical balance for pool closing

Calcium Hardness

If pH is high maintenance, calcium hardness only requires a check in every now and then. Your optimal calcium hardness level is going to be anywhere between 150 and 400 ppm—and that’s a huge range. If it falls below 150 ppm, it could stain and etch your pool. And if it’s too low during the pool season next year, it could corrode your pool plumbing—plus your heater, if you have one. If you have a super powerful and energy-saving unit like this ComforTemp Pool Heat Pump, then you’re going to want to make sure it lasts. 

Pool Shock

You’ve shocking your pool once every week (you have, haven’t you?) and this round is no different. That is, unless you have a recurring algae problem. Once the sun’s down (or anytime, if you have an indoor pool), go ahead and shock your pool to clear out all that inactive, microscopic junk that your chlorine leaves behind. If you do unwillingly host algae every so often, go ahead and add twice the recommended amount of shock to your pool. That’ll help to kill off any algae that you can’t actually see… yet.

Remember, pool shock is often considered a heavy-duty dose of chlorine, and is sure to affect your sanitizer levels. The optional chemicals mentioned in this next step should be applied when your sanitizer levels are back within the optimal range. This might take a few days. Hey, fair warning—and if you want to jump the gun, that’s totally up to you.

Not For Everyone: Algaecide, Pool Enzymes, Metal Sequestrant, Antifreeze

Now that you’ve got the essential chemicals done, we can get a little specific. These are the three “if, then” chemicals—you only need to apply them if you experience the issue they treat. 

1.     If you have an algae problem, you’ll want to add a dose of algaecide and pool enzymes to keep those microspores in check throughout the winter.

2.     If your water source is a well, if you know you have high levels of metals in your water, or if you’ve struggled with metal stains in the past, add a dose of metal sequestrant to your water. This will keep the metal in your water from attaching to any of your pool surfaces during the off season.

3.     If you deal with freezing temperatures in your area during the winter but didn’t blow out your pipes if you have an in-ground pool, or dissemble and store your plumbing if you have an above-ground pool, go ahead and add pool antifreeze down your pool’s plumbing line. Make sure your anti-freeze is clearly marked for pools—or else you could accidentally be pouring toxins into your water. Yikes. Nobody wants to have to drain their pool and start from scratch.

Remember, your winter cover is going to get some serious debris over the next few months—and left unattended under that weight, it could fall into your pool and bring all that gunk with it. To keep your cover light and secure, you’ll want a powerful, reliable, and heavy-duty cover pump like the BLACK+DECKER 1500 GPH Automatic Submersible Pump. It works on its own to detect water up to 1/8 inch and comes with a whopping 30 ft discharge hose and 25 ft power cord. Check out this user review to find out more.

how to get the perfect chemical balance for pool closing

You’re (Mostly) Done! 

Just like that and we’re back to balance. Even every season lasts about the same amount of time. And although we’re not exactly thrilled that we are done with swimming for the year—though we are looking forward to those reduced energy bills—at least we know that on pool opening day next year, we’ll have a pool and not a swamp to deal with. All you’ll need to do now is check your water balance on those few winter days that hit about 65 degrees Fahrenheit, if you have any. But for now, you’re in the clear. And while I can’t tell you to celebrate with a swim, your next one is going to be stress-free, thanks to what you did today. Until then, enjoy.


Related articles:

Sand in Your Pool? Here’s Why—And How to Fix It

Chlorinate Your Pool in Three Easy Steps

The Safest Way to Store Your Above Ground Pool For Winter

Above ground poolAbove ground poolsIn-ground poolsPoolPool accessoriesPool equipmentPool maintenance