How to Balance Hot Tub pH—Fast

It’s normal to step out of the warm, bubbling waters of your hot tub and experience a flush to your skin. That’s just the heat. But what’s not normal is when the flush persists well after your towel-off, and then… ah ah ah… starts to itch. 

If you’ve got skin irritation from a sting to a full-blown rash, or hair that feels like it’s never seen the inside of a conditioner bottle, there’s a chance the pH in your hot tub is well overdue for a rebalance. But don’t wait until your body protests. You should be checking your pH every week, and balancing as needed.

We’ll go over why hot tub pH is important to get right, how pH functions in the first place, and how to nail yours—fast. Let’s go.

Why Bother with Hot Tub pH? 

Hey, I get it. The whole point of having a hot tub is to relax, right? So it’s easy to wonder why you’re also spending so much time trying to maintain a complex balance of chemicals. 

If you’re new to this game, let me just say this: once you get used to balancing your pH and other chemicals, staying on track is a walk in the park.

It’s also just so, so worth it. This goes back to the same philosophy that applies to most of the weekly, monthly, and yearly maintenance recommended to pool owners: Prevention. Is. Everything.

The amount of time that you spend maintaining pH and other chemicals is just a fraction of the time you’d have to spend later down the line otherwise. 

In the case of pH, you’re putting your spa (and in some cases, yourself and other swimmers) at risk if your levels spike too high or drop too low. 

The Basics (ha!) of pH 

This is just in case one particular high school chemistry lesson didn’t stick. You might remember learning about the pH scale, which ranges from 0 to 14. Any solution that tests below 7 is acidic, above 7 is basic, and right at 7 is neutral. Maybe you even tested lemon juice and soap. 

If you did, great: that class actually prepared you for the real world. If you don’t remember, it’ll still be a cinch to master.  

Using water test strips, check to see how acidic, basic, or neutral your hot tub is. The pH levels in your spa should measure between 7.4 and 7.6. 

Now, that’s a pretty narrow range. But in order to keep your swimmers and your hot tub safe, you’ll want to nail it.

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. 

Low pH has a High Risk

You never want your pH level to dip below 7.4—especially far below 7.4. The lower your hot tub’s pH, the more acidic it is.

Here’s why that’s a bad thing.

Highly acidic water will stop your sanitizer from working efficiently. That means that swimmers in your spa are less likely to be alone: a whole host of bacteria will join them. Sometimes, that bacteria can be harmful.

This scenario can be even worse than inefficient sanitizer in a swimming pool. That’s because hot tubs operate at much higher temperatures than pools—while the average pool temperature is between 78 and 82 degrees Fahrenheit, hot tubs are somewhere between 98.6 and 104 degrees Fahrenheit. Any temperature above 85 degrees is more welcoming to bacteria. That includes their offspring, since they’re more likely to reproduce at rapid rates in a nice, comfortable, warm pool of water.

Since untreated or mistreated hot tubs are more likely to host bacteria, there are some pretty nasty strains that have already been documented. This includes pseudomonas aeruginosa, which causes hot tub folliculitis, and legionella, which causes Legionnaires’ Disease. 

Bet you’re feeling pretty ready to keep your pH maintained right about now. 

There’s more: low pH can also cause corrosion on your equipment and plumbing. So keep yourself, other swimmers, and your hot tub healthy. Don’t let your pH drop below 7.4.

High pH Lowers Tub Value

Now you know that having a low pH level in your hot tub could lead to disastrous results. But that doesn’t mean the more basic your water is, the better. No way. 

Unfortunately, a too-high pH also prevents your sanitizer from working. Same problem, same bacteria. And same health risks. Yikes.

In addition to making your hot tub water straight-up unsafe, a pH reading above 7.6 will also increase your calcium hardness, form scale, and make your water cloudy. Gross. 

The Key: It’s Alkalinity 

Now that you know why achieving the perfect pH is so important, you’re itching to get straight to balancing.

Hold it right there.

Before you balance pH—or any other chemical, for that matter—you want to nail your total alkalinity. This should always be the first step in your weekly chemical balancing routine. 

So why is it important to balance total alkalinity first? It’s pH’s righthand man. If you’re not in pH’s inner circle, you might not know that it’s super, super sensitive—especially to environmental factors. Alkalinity acts as a buffer for pH by keeping it stable. 

The ideal level for total alkalinity is between 100 and 150 parts per million (ppm). Add it in small doses until you’ve hit it. Only then should you move on to balancing pH.

Did you know rain messes with pH? To save yourself the trouble of rebalancing, you’ll want to cover your hot tub and 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. 

How to Balance Hot Tub pH—Fast

This is where it gets a liiiittle tricky. You have the perfect total alkalinity levels now. But anything you do to your pH will also probably affect alkalinity. 

The key to not getting into a never-ending loop of adjusting pH and alkalinity? It all lies in the chemical you’re using, and the method.

How to Raise pH

There are many pH increasers on the market, but most of them use the same active ingredient: sodium carbonate. That’s the technical name for soda ash. 

Soda ash is not to be confused with baking soda. That’s better used for raising total alkalinity (and remember, we already did that). For pH, it’s soda ash all the way. 

But even though soda ash is the best chemical to use, it can also increase total alkalinity.  

So here’s a loophole. It goes all the way back to when you first used a water test strip to check your total alkalinity, pH, and other chemicals today. The thing is, pH and alkalinity are so close, and tend to be so affected by each other, that they’re pretty likely to be in the same headspace. In other words, if your pH is low, chances are your alkalinity is also low.  

If you can see that both of these levels are low right at the outset, you can aim a little lower when balancing alkalinity. That’s because you know you’re about to raise pH, and you know that doing that will probably also increase alkalinity. 

Genius, right? So even though you do balance alkalinity before pH, a little foresight never hurt anyone. 

When adding soda ash, you want to distribute it evenly across the surface of your hot tub water. It’s best to do small increments and test as you go, so you don’t get stuck in a balancing loop. Stop adding when the pH starts to test somewhere between 7.4 and 7.6.

How to Lower pH

Just like pH increasers, pH decreases also tend to share the same active ingredient. In this case, that’s sodium bisulfate. 

You already learned how to increase pH, so you’ll be a pro at this. The same loophole applies: sodium bisulfate might lower your total alkalinity, though usually not significantly. It’s good to work incrementally, here. When you first balance alkalinity and you know you’ll lower pH next, aim for the higher end of the spectrum. 

That’s the trick to getting this done in one.  

When you’re ready to adjust pH, apply sodium bisulfate to the surface of your spa water in long even strokes. Again, just do a little at a time, and keep testing as you go. 

Another option other than sodium bisulfate is muriatic acid, but I don’t usually recommend it. It’s an extremely dangerous chemical to use, and requires dilution and a whole lot of time. It’s sodium bisulfate all the way for me.

Really loving that warm water—and feeling like your pool should follow suit? Heat your swim to a comfortable degree with the Energy-Saving ComforTemp Pool Heat Pump 95,000 BTU to heat 18,000 Gallons. According to customer Steve, “Simple install and simple set up. Heated my pool from 66 to 82 degrees in about 2 complete days.”  

You Nailed It! 

So long, skin rash. Now that you know how to balance pH quickly, it’ll be no problem to get this step of your maintenance routine done every week—even when your errands stack up. You’ve earned a comfortable, safe soak for your equipment, your tub, and you. 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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