The Pool Is Breathing (And Nobody Told You Why) - Friday

This week on Floc-It Friday, Rudy Stankowitz takes aim at one of the most misunderstood concepts in pool chemistry: pH drift. If you've ever been told that pH "just goes up," Rudy has news for you. Water doesn't drift. Chemistry doesn't shrug. And carbon dioxide may be controlling your pool far more than you've been taught. 

Before diving into chemistry, Rudy opens with a satirical pool industry news segment covering algae in Washington's Reflecting Pool, Leslie's recent financial improvements, private equity acquisitions, above-ground pool recalls, and the growing obsession with smart pool equipment. 

Topics Covered

Breaking News from the Pool World

A tongue-in-cheek look at:

•  Algae growth in the Reflecting Pool near the National Mall 
•  "Operation Green Freedom" and a fictional crop-duster copper sulfate deployment 
•  Leslie's reporting improved sales and customer activity 
•  Ongoing consolidation of pool service companies through private equity acquisitions 
•  Above-ground pool recalls making national headlines 
•  The industry's growing fascination with app-connected heat pumps and automation 

Why "pH Drift" Is a Bad Explanation

Rudy challenges one of the industry's most common phrases.

Water does not mysteriously "drift."

When pH changes, chemistry is causing it.

This episode explains why saying pH drift is often an observation rather than an explanation and why understanding the underlying chemistry matters. 

The Pool Is Breathing

One of the most important concepts discussed:

Your swimming pool is continuously exchanging gases with the atmosphere.

Topics include:

•  Gas exchange at the air-water interface 
•  Chemical equilibrium 
•  Carbon dioxide movement 
•  Why pools are dynamic systems rather than static containers of water 
•  How atmospheric chemistry influences water chemistry every second of every day 

Carbon Dioxide: The Hidden Driver of pH Rise

Most pool professionals focus on chlorine, alkalinity, calcium hardness, and acid additions.

Rudy explains why carbon dioxide deserves far more attention.

Learn about:

•  Carbon dioxide dissolution 
•  Carbonic acid formation 
•  The carbonate buffering system 
•  Why carbon dioxide leaving the water causes pH to rise 
•  The relationship between carbon dioxide, bicarbonate, and carbonate chemistry 

Eric Knight's Brilliant Cyanurate-Alkalinity Explanation

Referencing the June 3rd episode of Rule Your Pool, Rudy revisits Eric Knight's explanation of why cyanurate alkalinity is treated differently depending on the calculation being performed.

Discussion includes:

•  Why cyanurate contributes to total alkalinity 
•  How muriatic acid protonates cyanurate ions 
•  The difference between cyanurate ions and cyanuric acid 
•  Why total alkalinity and carbonate alkalinity are not interchangeable 
•  When to use carbonate alkalinity for LSI calculations 
•  Why total alkalinity is still used for acid demand calculations 

Does pH Still Matter When CYA Is Present?

A detailed review of:

•  The FC/CYA relationship 
•  Hypochlorous acid concentration 
•  The effects of pH on sanitizer strength 
•  Why maintaining the proper chlorine-to-CYA ratio matters 
•  Pathogen kill times at different pH levels 
•  Giardia and leptospira examples demonstrating how pH can still influence disinfection performance 

Total Alkalinity Is Not a Chemical

One of the central lessons of the episode:

Total alkalinity is a measurement, not a substance.

Topics include:

•  Buffering capacity 
•  Acid neutralizing capacity 
•  Carbonate and bicarbonate systems 
•  Why alkalinity gets blamed for everything 
•  The difference between cause and effect in water chemistry 

Le Chatelier's Principle and Pool Chemistry

Rudy breaks down one of chemistry's most important concepts into practical pool language.

Learn:

•  What happens when equilibrium is disturbed 
•  How the carbonate system responds to carbon dioxide loss 
•  Why hydrogen ion concentration changes 
•  The actual mechanism behind rising pH 

Why Waterfalls, Spas, Bubblers, and Deck Jets Raise pH

If your backyard resembles a miniature Bellagio, this section is for you.

Topics include:

•  Aeration and turbulence 
•  Increased gas exchange 
•  Carbon dioxide stripping 
•  Why decorative water features often accelerate pH rise 
•  Understanding the relationship between aeration and water balance 

Salt Systems and pH Rise

A common misconception is addressed:

Salt systems do not create pH.

Instead, they create conditions that accelerate carbon dioxide loss.

Discussion includes:

•  Hydrogen gas production 
•  Increased turbulence 
•  Gas transfer dynamics 
•  Why salt pools often experience persistent pH rise 

Acid and Aeration: The Ultimate Demonstration

Rudy explains why the classic acid-and-aeration method for lowering total alkalinity proves that carbon dioxide—not alkalinity—is driving pH rise.

A practical chemistry lesson every service technician should understand. 

Key Takeaways

•  pH does not mysteriously drift. 
•  Carbon dioxide is often the real driver of pH rise. 
•  Total alkalinity is a measurement, not a chemical. 
•  Aeration accelerates carbon dioxide loss. 
•  Salt systems indirectly contribute to rising pH by increasing gas exchange. 
•  Understanding equilibrium makes pool chemistry easier to predict. 
•  Once you understand carbon dioxide, many long-standing pool chemistry mysteries disappear.

Transcript

SPEAKER_01 0:00

Welcome to Friday. I am Rudy Stankowitz. This is the Talking Pools Podcast. And again, the day before the weekend, I hope today kicks ass for you and you get everything done that you wanted to get done. So this way, you know what? You gotta absolutely not a damn thing work related that you have to do tomorrow. And if you have to work tomorrow, please at least make yourself some time to kick your feet up on Sunday. Do something good. Something with the family. Do something with the kids. Go fishing. Go for a hike. Just do something. Something that doesn't involve chlorine. How about that? We interrupt this recording with breaking news. Washington, D.C. Panic has erupted this morning as officials confirmed extensive algae growth has been discovered in the reflecting pool near the National Mall. Witnesses described the water as having transitioned from historic monument to lightly seasoned pond sometime during the past several weeks. Tourists arriving at the scene reported confusion. I thought it was supposed to reflect monuments, said one visitor from Ohio. Right now it's mostly reflecting poor phosphate management. Federal officials have not yet released water chemistry findings, though unconfirmed reports suggest the algae has established what the experts are calling a thriving homeowners association. As crews scramble for solutions, cool industry officials from across America have begun offering unsolicited advice at unprecedented levels. Social media erupted overnight, one faction demanded immediate phosphate removal, another blamed inadequate circulation, a third group insisted the problem could only be solved by replacing all the water, acid washing, the Lincoln Memorial, and starting over. Meanwhile, local government officials have reportedly assembled a task force consisting of engineers, environmental scientists, biologists, chemists, historians, three consultants, seven lawyers, and one guy named Steve who has a pond. However, one proposal is quickly gaining attention. Pool educator Rudy Stankowitz has reportedly drafted a comprehensive emergency response plan involving a vintage crop duster flying nap of the earth over the reflecting pool while dispersing chelated copper sulfate at tactical altitude. According to sources familiar with the proposal, the operation will be called Operation Green Freedom. The plan reportedly includes low-level aerial deployment, dramatic patriotic music, excessive use of aviation terminology, at least one pilot wearing aviator sunglasses, a post-treatment phosphate reading conducted while an eagle flies overhead. Criticals argue the plan may face regulatory challenges. Supporters counter that regulatory challenges have never stopped to determine pool guy with a chemical calculator and a dream. Press time officials had not responded to requests for comment, though sources indicate someone in Washington accidentally forwarded the proposal to the Department of Defense, where it is reportedly receiving serious consideration more as this story developed. In other news, let's talk Leslie's. Remember six months ago when half the industry was convinced Leslie's was one earning report away from becoming a spirit Halloween? Well, apparently not. The company is reporting improved sales, more customers, and signs that the patient may in fact still have a pulse. Critics remain skeptical, supporters are optimistic, and cool guys everywhere continue walking into Leslie's to buy chlorine while simultaneously explaining why nobody should ever shop there. It is one of the great mysteries of our time. In other news, private equity firms continue collecting cool companies like Gen X collected baseball cards every week. Another service company gets acquired. At this rate, by 2030, your local one truck pool guy will either be retired, working for a corporation, or operating out of an undisclosed bunker somewhere in rural Missouri. Industry experts call it consolidation. Pool guys call it, wait, they paid how much for that route? Moving on. The above-ground pool recall continues making headlines, millions of pools, years of sales, one design feature nobody thought would become a foothold. It is a reminder that engineering is important and that somewhere right now an attorney is purchasing a third boat. Meanwhile, manufacturers remain obsessed with heat pumps. Every equipment announcement sounds like a Tesla presentation, more efficient, smarter, connected to an app, tracks your energy use, probably knows your cholesterol level. At this point, I'm surprised the heater doesn't send motivational text messages. Great job, cool guy. Finally, the biggest story nobody is talking about service companies. While everybody argues online about phosphate, CYA, LSI, borates, ORP, and whether fluorine is a government conspiracy. Service companies continue quietly making money. For Talking Pools News, I'm Rudy Stankwitz, reminding America that every body of water is just one neglected test kit away from becoming a biology experiment. I've been getting Service Industry News since I first stepped into this business, and every time it landed, I did the same thing. Flip straight to the horror file. The weird installs, the absurd finds, the stuff only pool pros ever see. Then I'd go back and read the articles. Service Industry News is a twice-monthly trade publication for pool and spa service text, 24 issues a year, emailed free to over 10,000 texts and available on their app. Every issue covers nationwide industry news and real technical content you actually will use. Get your free subscription at serviceindustry news.net. Again, that's serviceindustry news.net. Do it now.

SPEAKER_00 5:36

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SPEAKER_01 5:51

Today, I want to talk a little bit about pH drift, but before I begin, I need to get something off my chest. I am convinced that half the pool industry learned chemistry from a guy named Vinny leaning up against a pickup truck in 1987. Seriously, because some of the explanations I hear make absolutely no damn sense. Customer says, My pH keeps going up, and immediately the theories start flying. It's the alkalinity, it's the salt system, it's the moon. It's because Mercury is in retrograde. It's because you looked at the pool funny. Nobody knows. Everybody's got a fucking answer, though. It's like asking twelve drunk uncles how to fix a transmission. You're gonna get 13 opinions in one fist fight. And here's the funny thing. Most of us were taught that pH just sorta drifts. What? What the hell does that even mean? Drift is what happens when your buddy Gary gets divorced at 52, buys a Camaro, starts tanning, and suddenly develops opinions about craftaquila. That's a drift. Water doesn't drift. Water obeys chemistry. Nobody ever walks into a chemistry lab and hears, well, the pH appears to be drifting. No. Some poor graduate student is buried under 600 pages of equations trying to explain why the damn thing moved. Meanwhile, in the pool industry, we're like, drift? That's not science. That's a shrug. And speaking of things we blame unfairly, can we talk about alkalinity? Poor alkalinity. That bastard gets blamed for everything. High pH, alkalinity. Scale, alkalinity. Cloudy water? Alkalinity. Dog won't listen. Alkalinity. Marriage fell apart. Could be alkalinity. At this point, alkalinity should have its own public defender. Maybe a talk show. Ladies and gentlemen of the jury, my client was nowhere near that calcium deposit. And don't even get me started on salt pools. Salt pool owners are like Harley writers. They always find a way to tell you. You don't ask, they just tell you. It's a salt pool. Really? I couldn't tell from the six gallons of acid sitting next to the equipment pad, like empty whiskey bottles after a bad weekend. Every salt pool owner eventually reaches the same stage of grief and angry. Get mad. Then standing outside at sunset, a lone silhouette, holding a jug of muriatic acid, asking philosophical questions. Why? Why is it 8.2 again? I literally fixed you Tuesday. It's like dating someone who's working on themselves. You think things are getting better. Three days later, you're right back where you started. And then there are the backyard water feature people. You know who you are. You didn't want a swimming pool. You wanted the fucking Bellagio. Now you got 12 waterfalls, deck jets, bubblers, rain curtains, spillover spas. Your backyard looks like Poseidon won the freaking lottery. And then you call me. My pH keeps rising. Really? You have enough turbulence back there to launch a bass boat. The ducks need hearing protection. The neighbors think you've installed hydroelectric power. Of course, your pH is going through the fucking roof. Your pool isn't swimming anymore. It's auditioning to become bad weather. And the whole time we're blaming alkalinity, blaming chlorine, blaming salt systems, blaming manufacturers, blaming the guy who installed the pool. The real culprit has been standing right in front of us. Carbon dioxide. That's right. The same stuff you exhale. The same stuff plants eat. The same stuff in beer. The same stuff in soda. The same stuff you spent your entire career almost completely ignoring. Carbon dioxide is like the quiet accountant in a mob movie. Nobody notices him, nobody suspects him. Meanwhile, he's running the whole damn operation. Because here's what nobody explains. Your swimming pool isn't just sitting there, it's breathing. Every second, every minute, every hour, it constantly takes a breath, exchanging gases with the atmosphere. Carbon dioxide coming in, carbon dioxide going out. The water and the atmosphere are having an ongoing chemical conversation, whether you know it or not. And once you understand the conversation, everything changes. Suddenly, pH rise isn't mysterious. Suddenly, alkalinity starts making sense. Suddenly, waterfalls, spas, bubbles, salt cells, and aeration all connect together. And you realize the industry has spent decades teaching the symptom instead of the cause. So grab a cup of coffee, put down the acid jug, stop blaming alkalinity for Christ's sake. It didn't commit any f crimes. Let's talk about the invisible gas that may be controlling your pool more than chlorine ever did. If you want your brain to hurt a little, I want you to roll back time to the June 3rd episode of Rule Your Pool with Eric Knight. Eric made a point. I think a lot of people realizing how important it actually was. We had been discussing earlier why we subtract cyanurate ions from the total alkalinity when calculating the saturation index. Eric just explains something brilliant. It's a question that never comes up, but it came up, one of his listeners asked. We know the cyanurate ion contributes to total alkalinity. Meaning when you run a total alkalinity test, some of what you're measuring isn't carbonate alkalinity at all. Some of it is cyanurate alkalinity. Now, here's where it gets kinda interesting. When you add muriatic acid to a pool, that cyanurate ion can accept a hydrogen ion, a proton, from the acid you added. Because it too is a buffer. Once it accepts that proton, it's no longer a cyanurate ion. It becomes cyanuric acid. And cyanuric acid are you sitting down? Does not contribute to the total alkalinity, at least not the same way cyanurate ions do. So think about that for a second. The acid didn't destroy the cyanuric acid, didn't remove the cyanuric acid from the pool, it simply changed its form. The molecule is still there. But because its chemistry changed, its contribution to total alkalinity has also changed. Now that's a huge concept because it demonstrates something that pool operators often miss. Total alkalinity is not a chemical, it's a measurement of the acid neutralizing capacity of several different species in the water. Carbonates contribute, bicarbonates contribute, hydroxides, cyanurates, chlorates contribute. Several things can participate, which is why when we calculate the saturation index, we don't use total alkalinity. We use carbonate alkalinity because calcium carbonate scaling doesn't care about cyanurate alkalinity. The LSI is specifically concerned with the carbonate system. But here's the part that Eric explained so well. When we're calculating how much myriatic acid to add to lower total alkalinity, we absolutely use the total alkalinity reading as is your test kit results without accounting for the contribution of cyanuric acid. We don't want the carbonate alkalinity for this one. We want the total alkalinity because the acid doesn't care what the buffering capacity came from bicarbonate, carbonate, cyanur, or borate, another weak acid system or whatever. The acid reacts with all available proton accepting species. That's what alkalinity measures. The total capacity of water to consume acid, and that's why people sometimes get confused. They hear us say subtract cyanurate alkalinity. Then we think, should we subtract it everywhere? No, only when we're isolating the carbonate system for the saturation index, for acid demand calculations, for alkalinity adjustments, for determining how much buffering capacity exists in the water. We want the whole picture. We want total alkalinity. Eric's explanation was one of those rare moments where a complicated concept suddenly became obvious and easily digestible. Once you understand that alkalinity is not a substance but a measurement of proton accepting capacity, a lot of pool chemistry suddenly starts making sense.

SPEAKER_02 14:37

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SPEAKER_01 15:10

It is true that pH matters less for chlorine effectiveness when the CYAFC ratio is held at that 7.5%. The blotchied table three proves it. Hypochlorous acid percentage swings plus or minus 1.8% from pH of 7.0 to a pH of 8.0 when the ratio is controlled. That's important. That's 7.5% level of chlorine in comparison to the total part per million of cyaneuric acid. But if you hold the free chlorine and caneuric acid at a static number and not the suggested ratio, for example, if we had our free chlorine at one part per million with 50 parts per million of cyanuric acid, total alkalinity of 80 parts per million, calcium hardness at 300 parts per million, and a temperature of 86 degrees Fahrenheit, then pH still controls the hypochlorous acid concentration. At one part per million free chlorine plus 50 parts per million cyaneuric acid, you've got 0.0112 parts per million hypochlorous acid at 7.0 and 0.0037 part per million of hypochlorous acid at 8.0. That's three times the difference. That's 200% greater in kill power from pH of 7.0 to 8.0 in the presence of 50 parts per million of cyanic acid. Now this is based on hypochlorous equilibrium calculations using a pKa of 30 degrees Celsius. What that means in the real world, bacteria and viruses still seconds to one to two minutes in either direction, but your safety margin is razor thin. Giardia, 68 minutes at a pH of 7.0, chlorine level of one part per million, again cyanuric acid at 50 parts per million, three hours at a pH of 8.0. So 68 minutes at 7.0, 3 hours at 8.0. So kill time stretch out. CDC or CMAC calls giardia a 45-minute problem at 2 parts per million free chlorine for a reason. Leptospirosis lab data shows 0.5 to 3 parts per million chlorine is lethal to leptospires. At 0.0037 parts per million hypochlorous acid at a pH of eight, you're talking hours, not minutes. Pathogenic leptospires are fragile, but you gave them time by having a higher pH. It's important to remember that pH does contribute to be a factor in LSI, algae growth, dissolution rates, and percentage of free chlorine lost due to solar UV degradation. All that information can be found in the following papers. Assessing the impact of cyanuric acid on bather's risk of gastrointestinal illness, falk et al. Effective chlorine on giardia lambia cyst viability, geril et al. Efficiency of chlorine investigation of giardia in wastewater, PLOS1, and agents known to kill leptospiers at leptosporosis.org.

SPEAKER_05 18:17

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SPEAKER_04 18:47

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SPEAKER_01 18:54

One of the most commonly repeated phrases in the pool industry is that pH drifts upward. Pool stores say it, manufacturers say it, even service technicians say it. I've even said it, as well as many other instructors. I know your customers say it. The problem is that it really doesn't explain anything. It's kind of a lazy way of saying that the pH moved. Imagine a student in a chemistry classroom raising their hand and asking why did the pH go up? And the teacher responds, Because it drifted. That's not an explanation. That's an observation. You guys are better than that. It's like asking why a car moved and being told because the wheels turned. What the fuck? The wheels turning are not the cause, they're the result. To understand why pH rises in many swimming pools, you gotta stop thinking like pool operators and start thinking like chemists. And that means we need to begin with something most people never even consider. Pool is breathing. Most people think of a swimming pool as a giant container of water. I mean it is, but a chemist sees something very different. A chemist sees a system. A swimming pool is continuously interacting with the atmosphere every second, every day. Even when nobody is swimming, even when the pumps are off, even when the water appears perfectly still, at the molecular level, movement never stops. Oxygen molecules are entering the water, oxygen molecules are leaving the water. Nitrogen molecules are entering and leaving. We have nitrogen fixing cyanobacteria. We've spoken about that. It brings atmospheric nitrogen into the water. We have denitrifying bacteria, which actually forces nitrogen back into the atmosphere. Water molecules constantly evaporating, and carbon dioxide molecules are constantly moving back and forth across the air-water boundary. The pool is effectively breathing. Doesn't mean that it's alive, it just means that it's interacting with the atmosphere. Don't get all weird on me, it's not in the biological sense, it's in the chemical sense. Every molecule in the water is participating in an ongoing negotiation with the atmosphere. Water and the air are constantly attempting to reach balance. Chemists call this equilibrium. Equilibrium is one of the most important concepts in all of chemistry. Whenever two systems are connected, nature tends to push them toward balance. High concentrations move toward low concentrations. Energy moves toward lower energy states. Pressure differences equalize. Temperature differences equalize. Chemical systems seek equilibrium. They just do. The atmosphere and your swimming pool are no different. Most people think of air as nothing. Can't see it, can't be there, ain't nothing in it. You know better. Air is a mixture of gases, roughly 78%. Nitrogen, roughly 21% oxygen, a very small amount of carbon dioxide, and then a bunch of trace amounts of other gases. That carbon dioxide concentration seems tiny, yet it controls a tremendous amount of what happens inside swimming pool water. Because carbon dioxide exists in both the atmosphere and in the water. Whenever the concentration in one place is greater than the concentration in the other, molecules begin moving about. The atmosphere and the water are constantly exchanging carbon dioxide. The question is not whether carbon dioxide is moving. The question is which direction is it moving in. When people think about pool chemistry, they think about chlorine, they think about acid, they think about alkalinity, they might think about calcium. I hope they do. Almost nobody thinks about carbon dioxide. Yet carbon dioxide may have more influence on day-to-day pH behavior than any chemical added from a bucket. Why? Because carbon dioxide does not simply dissolve into water and sit there. It becomes part of an interconnected chemical system. Once dissolved, carbon dioxide can exist in multiple forms. Some remains dissolved gas, some combines with water, some forms carbonic acid, some becomes bicarbonate, some becomes carbonate. Chemists refer to this collection as the carbonate system, and the carbonate system is one of the primary buffering systems in swimming pool water. When most people hear the word acid, they imagine muriatic acid, strong, aggressive, corrosive. Carbonic acid sounds harmless by comparison, but carbonic acid is one of the most important acids in pool water. When CO2 dissolves into water, CO2 again being carbon dioxide dissolved into water, some of it reacts with water molecules and forms carbonic acid. Carbonic acid is weak. That does not mean it's unimportant. Weak acids often play enormous roles in chemistry because of their abundance. Carbonic acid acts as a reservoir of acidity. It continuously exchanges with other forms in the carbonate system. The system is never static. Molecules are constantly changing forms. Carbonic acid becomes bicarbonate. Bicarbonate becomes carbonic acid. Carbon dioxide leaves the water. More carbon dioxide forms. The system is dynamic, always changing, always adjusting, always seeking equilibrium. Most pool operators know how to test total alkalinity. Far fewer understand what it actually means. Total alkalinity is not a chemical. We said that a moment ago. It is not a substance. It is not something floating around in the water. It is a measurement. Specifically, it is a measurement of the water's ability to resist downward changes in pH. Think of alkalinity as the shock absorbers on a truck. Without shock absorbers, every bump in the road is transmitted directly to the vehicle. The ride becomes violent. Buffers work similarly. Without buffering, every addition of acid or base would cause dramatic pH swings. And that's what pH bounce is. It's not something that happens by itself.

SPEAKER_03 25:35

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SPEAKER_04 26:10

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SPEAKER_04 26:31

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SPEAKER_01 26:32

I know you've been told if the total alcohol energy is low, your pH will bounce. And some folks think that means it just moves all over the place by itself, up and down like an EKG line. No rhyme, no reason. That's not the case. It takes a catalyst. So look at it like this instead. Something that should only affect the pH a little bit affects it drastically. Like a rain rolling through. Rainwater is acidic. I'm not talking acid rain, that's super acidic. But rainwater is acidic after a rain. If your pool started with a pH of 7.5, if it was a good solid rain, I would expect to see that it was 7.3 after the storm had passed. However, if that same rainstorm had taken my pH from 7.5 and I'm suddenly at 7.0, that's what I would call pH bounce. So the carbonate system absorbs those impacts. It's what deadens the acidic of the rainwater or deadens the acidity of anything that goes in, it absorbs changes. Carbonic acid absorbs some changes. Bicarbonate absorbs others. Together, they stabilize the water. That stability is what we measure when we test total alkalinity. We're taught that a high alkalinity causes pH rise. That statement's only a little bit true. High alkalinity does not force the pH upward. What high alkalinity does is increase the size of the carbonate reservoir. Imagine two fuel tanks. One holds ten gallons, the other holds fifty gallons. The larger tank does not make the vehicle move. It simply provides more fuel that can potentially be used. High alkalinity works the same way. Higher alkalinity means more bicarbonate. More bicarbonate means a larger carbonate reservoir. A larger carbonate reservoir means carbon dioxide can potentially be generated and eventually lost. But the actual rise in pH still occurs because carbon dioxide leaves the water, not because alkalinity itself somehow pushes pH upward. If there is one chemistry concept that explains pH rise in pools, it is Le Chateliers, which I'm sure I said wrong, Le Chatelier's principle. That Shear's principle states that when a system at equilibrium is disturbed, it responds by shifting in a direction that opposes the disturbance, translated into plain English. When you mess with the chemical system, the system pushes back. Suppose carbon dioxide leaves the water. The carbonate system immediately becomes unbalanced. Nature hates imbalance. The system responds by trying to replace the lost carbon dioxide. Some carbonic acid converts into carbon dioxide. Some bicarbonate converts into carbonic acid. As these conversations occur, hydrogen ions are consumed. As hydrogen ion concentration decreases, pH goes up. Nothing was added. No alkaline substance entered the water. The chemistry simply rearranged itself to restore balance. That's the true explanation for pH rise. And of course, as we had mentioned in earlier episodes, if rising pH is your problem, a lower target total alkalinity may be your solution. Shoot for 60 ppm. At 60 ppm, CO2 dissolves better in water. If it dissolves better, it is harder at outgas. Now we can understand why waterfalls, spas, fountains, deck checks, and splash features affect pH. Most people think aeration is a circulation issue. Chemically, aeration is a gas transfer issue. Whenever water becomes turbulent, the surface area between water and air increases dramatically. More surface area means faster gas exchange. Faster gas exchange means faster carbon dioxide loss. Faster carbon dioxide loss means a stronger disturbance to that equilibrium, which means a stronger response from the carbonate system. That response consumes hydrogen ions. As hydrogen ions decrease, pH rises. Nothing was added. Carbon dioxide simply left faster. Salt water chlorine generators create chlorine through electrochemical reactions, and at the same time they produce hydrogen gas that bubbles. Those bubbles increase turbulence. They increase gas exchange. They increase carbon dioxide loss. The cell effectively becomes a miniature carbon dioxide stripping device. How's that for thought? Miniature carbon dioxide stripping device. Sounds like something I saw written on the bathroom wall in high school. A lot of pool pros assume the salt system is creating pH. It's not, and I know a lot of you don't, nobody here that listens to this show thinks that. Maybe somebody that listens to something else. I don't know. But it doesn't do that. The system is creating conditions that accelerate carbon dioxide removal. The chemistry that follows is exactly the same chemistry we have already discussed. One of the most powerful demonstrations of this chemistry occurs every single day in the pool industry. The acid and aeration method used to lower total alkalinity. First, acid is added, pH drops, the carbonate system shifts, carbon dioxide concentration increases, then the water is aerated. Carbon dioxide leaves the water, the pH rises again, yet alkalinity remains lower. The experiment proves that pH rise is not being caused by alkalinity. If alkalinity directly caused pH rise, this process wouldn't work. Yet it works every single time because carbon dioxide is the true driver. The phrase pH drift makes pH rise sound kind of mysterious, so I get it. It's not. The chemistry is doing exactly what chemistry is supposed to do. The pool is continually exchanging gases with the atmosphere. Makes sense, right? Carbon dioxide enters, carbon dioxide leaves. The carbonate system responds. Equilibrium is disturbed. Equilibrium is restored. Hydrogen ion concentrations change, pH changes. What we call pH drift is often nothing more than the visible result of an invisible gas leaving the water. The pool is not misbehaving. The chemistry is not broken. The water is simply obeying the laws of physics and chemistry. And once you understand carbon dioxide, you stop chasing pH numbers and start understanding why those numbers move in the first place. I'm Rudy Sankowitz. This is the Talking Pools podcast. Until next time, be good. Be safe.