What’s the Deal with pH in Pools?

I promise, this is not going to be a repeat of your high school chemistry class. I’m not going to reprimand you for messing around with a Bunsen burner during the lecture, explain how to use the classroom emergency shower if something goes terribly wrong, or make you stay up late memorizing the periodic table for tomorrow’s exam. Here, we’re sticking only to what’s relevant for you and your pool. And pH? It couldn’t be more essential to understand to keep your swim both comfortable (you know, enjoyable) and safe. Here I’ll explain what pH is, why it matters, and how to adjust it in a pool and a hot tub—without once making you feel like you’re fifteen again. Sound good to you? Let’s do it.

Wait, What’s pH Again?

When talking about pool chemistry, we tend to focus on the sanitizer—whether that be chlorine tablets, a saltwater generator, or any of the other sanitizer options on the market. And sanitizer is definitely important. Without it, your pool just isn’t a safe place to be. But other than helping your sanitizer to stay effective, an optimal pH is also what makes swimming in your pool water actually enjoyable.

So what exactly is pH? Well, it’s simple: it’s a measurement of whether a substance is basic or acidic. It runs from a scale of 0 to 14, and 7 is neutral. Any measurement higher than 7 is basic, and anything below 7 is acidic.

Ideally, your pH should be between 7.4 and 7.6, which is pretty close to the 7.4 pH of our eyes and mucus membranes. And that is exactly how the pH of the water around you determines your comfort. If our water is more acidic, our eyes would seriously sting. If we’re swimming in water that’s more basic, our eyes and noses would dry out.

But pH isn’t something that you balance once and are done with forever—unfortunately, no pool chemical is. It’s affected by anything that comes into contact with your pool, including rain, debris, and yes, even you. Thankfully, all it takes is a few minutes every week to keep tabs on your pH.

Ph in pool

Whatever chemicals you add to your water don’t just spread evenly on their own. You’ll need a reliable, powerful, and energy-saving pump like the 2 HP Energy Star Variable Speed In Ground Blue Torrent Cyclone Pump to make sure all your water is treated. Plus, it comes with a lifetime warranty, is eligible for rebates, and pays itself off in under a year. According to customer Dave Schmidt, “my pool has never looked cleaner!”

Why Should I Even Bother with pH?

If you’re a regular at your local health market, you know that a certain pH in drinking water is a recent wellness craze. And as with all health trends, the science is either catching up or unsupportive. But as far as the water that you swim in, it’s clear that the pH does matter—and you don’t have to read a single scientific study to know for yourself. If the pH of your water is above 7.6 or below 7.4, you’ll feel the difference. And if it’s far off from those numbers? I have one word for you: yowch!

pH Too High

Remember, pH too high is getting seriously basic. When this happens, you can expect your water to start clouding, and damaging scaling to build up on that pool equipment you work so hard to maintain. But that’s not the worst of it: high pH also affects your sanitizer’s ability to work efficiently. Have a high pH for long enough, and you’ll be swimming with a ton of gross bacteria, including the kind that could potentially make you sick. 

But I also said you’ll feel the difference: swimmers in pool water with a high pH are at risk for skin rashes, red and irritated eyes, even premature wear on their swimsuits and goggles. I don’t know about you, but I’m not loving the idea of water that could eat up fabric. Yikes.

pH Too Low

Okay, so we know that the last thing we want is a high pH. So why not just let it fall as low as possible? Well, we don’t want acidic water, either. Just like alkaline water, low pH will prevent chlorine from doing its job, and require a lot more chlorine to be added to your pool to reach the proper sanitization level. Acidic water can also wreak havoc on your heat pump—which, you know, doesn’t come cheap—and eat away at your pool tiles, if you have them, which will also give algae a nice rough surface to hold onto. And this one might be surprising: it can even turn your pool water from brown to black. Uhh, pass on that one.

Since both are far from the natural pH of the human body, the same swimming drawbacks of basic water also apply to acidic water: you can expect red, irritated eyes and skin rashes. Plus, your swimwear will wear out fast and can even bleach. This one’s intense, my friend. 

One major wrecker of pH? That would be algae, no question. Use the BLACK+DECKER 360-Degree Bristles Pool Brush to keep microspores from attaching to your pool walls and floors. It was developed by longtime pool maintenance experts to prevent aches and pains associated with getting hard-to-reach corners.

Ph in pools

pH and Alkalinity: A Love Story 

It’s impossible to talk about pH without mentioning its chemical partner, alkalinity. This chemical acts as a buffer by absorbing any kind of major changes to the water before those changes can alter your pH. This way, alkalinity prevents your pH from any kind of dramatic fluctuations.

But any changes to your alkalinity level will also ripple out to change your pH. The best way to tackle this problem? Always adjust your alkalinity first: it should be 125 parts per million (ppm), but anything between 100 ppm to 150 ppm is good to go. 

Although you might have an alkalinity increaser already (or baking soda, which also does the trick), I’m willing to bet you don’t have an alkalinity decreaser. That’s because it doesn’t exist. If your alkalinity is high, a pH decreaser will lower it. Yes, it’ll lower pH as well. Once the alkalinity is where you want it, use a pH increaser to bring up your pH again. 

Get the Gear

Don’t worry, you’re not going to break the bank for this one. All you need to have on hand is a pH increaser, a pH decreaser, test strips, gloves, and safety goggles. Looking great! 

How to Adjust pH in a Pool 

Now we’ve made it to the fun part. Or the boring part. Honestly, it depends on how you spend your time between adding the chemicals. Let’s say you’re here because you noticed that your pool water is stinging a bit more than normal, or you already adjust your pH but want to make sure you’re doing it right. In either case, I’ll show you how to start fresh with an optimal pH level.

First, use a water test strip to see where your pH level is right now. Remember, the optimal pH is 7.4 and 7.6. If your number is below that, you’re dealing with an acidic pool. If your number is above that, your pool is basic. And haven’t you heard? That’s the swimming pool equivalent of pumpkin spice lattes. 

As with all chemicals you add to your water, circulation is key. For above-ground pools, you can determine that horsepower that’s right for you with the Single Speed Dual Port Replacement Pump. According to customer Lisa Dabrawsky, “Love the new pump. Before, I couldn’t sit outside with the old pump running. This one is so quiet. Thanks.”

Raising Your pH

  1. To fix that acidic water, first turn on your circulation system and have your pH increaser handy, which is usually sodium carbonate (though you’ll also hear it referred to as soda ash).
  2. Though you’ll want to follow the manufacturer’s instructions for this and every other chemical, you might need to dilute your pH increaser in a bucket of water and stir it around with a plastic or wooden utensil first.
  3. Next, add your pH increaser evenly around the perimeter of the pool, and away from fixtures and skimmers. It’s typically recommended that you add about one pound of a pH increaser per 10,000 gallons of your pool every four hours.
  4. Keep retesting before you add more. And once you find that you’ve hit your desired level, you’re done.

Lowering Your pH

  1. Kick that basic water to the curb—though this is not literally necessary, unless your chemical balance is so far off that you need to drain your pool. Again, you’ll want to turn on your circulation system for this process.
  2. Your pH decreaser will probably be muriatic acid or sodium bisulfate, which you might also need to dilute in a bucket of water.
  3. Then, add it directly to your pool water around the perimeter of the pool, and away from fixtures and skimmers.
  4. You’ll need to follow the dosage on your pH decreaser’s packaging, but it’s typically recommended that you add this chemical to your pool every four hours and keep retesting before adding more.
  5. Once your pH hits between 7.4 and 7.6, you’re done.

Ph in pools

How to Adjust pH in a Hot Tub

It’s little surprise that hot water requires a different set of chemicals—you don’t have to have ever gone to science camp to catch on to the fact that chemicals are super influenced by temperature. For increasing pH in a hot tub, you’ll want to use potassium carbonate. For decreasing pH, it’s all about sodium bisulfate.

The process is the same as adjusting the pH in your pool, but this time size is on your side: you’ll only need to add about one ounce per 500 gallons every thirty minutes. Don’t forget to retest your water before adding more so you don’t overdo it.

Remember, rain messes with pH—you’ll want to cover your pool for the less windy storms. Keep your cover light and secure with the BLACK+DECKER 800 GPH Automatic Pool Cover Pump, which detects up to a quarter inch of rain and works on its own—fast.

Now That Was Far From Basic!

Great work. See, I didn’t quiz you. But I didn’t need to: as long as you have test strips and the right chemicals on hand, balancing your pH is as straightforward as it gets in pool maintenance. And now that you’ve mastered the chemical that makes swimming feel good—and not, you know, painful—you’re sure to love all your future dives even more than ever. Class dismissed, and, as always: enjoy.


This article explains how you can backwash your pool filter efficiently. Want to know how to clean the bottom of your pool? Read more here.

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