My Pool Guy Is Full of Crap

So, my pool guy is full of crap. That's a real thing people say. I've seen it in the forums and in Facebook groups, in Reddit threads. Usually right after someone got a$200 chemical bill that did not make a lot of sense. Or an answer that felt like it came from someone who was guessing. And look, sometimes they're right. But I've been in this industry for a long time, and I'm here to tell you that most of the time, the pool guy is not the problem. The problem is what he was handed before he ever showed up at your pool. This episode is his defense. And if you're a pool guy listening to this, I think you're gonna feel a little better about your day at the end of it.

Welcome to the Pools Scientific Podcast, elevated pool care through science and technology. I'm John Cooper, chemical engineer, nuclear engineer, navy submarine veteran, five DHTA certifications, and yes, I'm a Fool Guy. Real Chemistry, Real Answers, every Tuesday. Let me tell you about a Tuesday. It's 7.15 in the morning. It's already 94 degrees Fahrenheit, that's 34 degrees Celsius, and the sun has been up for about an hour. Your pool guy is on his second stop. He's got 35 more pools between him and the end of his day. His chemicals are staged in the truck, his kit's ready, and he's moving. At stop number four, he's dealing with a pool where the homeowner flagged him down last week because the water looked a little off.

He went back, sorted it out, didn't charge extra. It's just part of the job. At stop eleven, he gets to the gate and realizes immediately that someone added shock the night before. Nobody texted, nobody left a note, the chemistry is off in a direction he was not expecting, and he has to recalculate on the fly, in the heat, before he can do anything else. At stop nineteen, the pool store calls while he's driving between accounts. They're running a special on stabilizer tabs. He half listens while watching his GPS and trying to remember if stop twenty has a gate code or a key. That is a Tuesday.

That is what this job actually looks like. And that guy, the one running that route in the heat, making those calls in real time, he learned what he knows however he could. Because in most states, the industry did not require him to learn it in any particular way. There is no licensing requirement for residential pool service in most of the country. No state board exam, no mandatory training hours. The credential you need in most markets is a truck, a route, a pole, and someone willing to pay you. So the typical path looks like this. You know someone who runs a route. They need help for the season.

You start riding along. You watch what they do. You learn to read a test strip, you learn backwash sequence, and you learn which chemicals go in first. And what you learn is what they know, which is what the person who taught them knew, which traces back eventually to a pool store training session, or a manufacturer rep with a product to move, or a three-day CPO course that gave you a laminated card and sent you home. That laminated card has a history to it. The CPO credential was developed in the 1970s for commercial aquatic facility operators, municipal pools, hotel pools, water parks, that sort of thing. Facilities with staff, with health department oversight, with turnover rates measured in thousands of gallons per hour.

That is what the curriculum was built around. Somewhere along the way it became the de facto credential for residential pool service too. Not because anyone decided it was the right fit, because it was the only card in the deck. A commercial aquatic certification became the training foundation for an industry that works in people's backyards. Nobody redesigned the curriculum to fit the work. The work just inherited the credential. The chain is long, and somewhere in that chain the reasoning got separated from the conclusion. What survives is just the conclusion. Change the sand every two to three years. Add two pounds of shock per week. Cyanuric acid is fine up to a hundred parts per million.

Bring a water sample to the store. High pH means your alkalinity is too high. Nobody along the way asks where these came from. They're just the things you say because the person who trained you said them, and the person before that said them, and nobody ran the chemistry. Now I come at this differently. I chose this industry with an engineering background already in hand. My job from day one was to look at what the industry was doing and ask whether the chemistry supported it. And honestly, a lot of the time it didn't. But what I found was not a profession full of people making things up.

It was a profession doing its best with inherited conclusions and no real mechanism for tracing them back to the source. So when someone says my pool guy is full of crap, I want to just pump the brakes a little. Because what I usually hear underneath that is my pool guy was handed some things that are not quite right, and he repeated them, and now I'm frustrated. That is a different problem, and it has a different solution. What I want to do for the rest of this episode is walk through five of the most common ones, the five things your pool guy is most likely getting wrong right now.

Not because he's cutting corners, but because nobody in the chain gave him the reasoning. And along the way, I want to talk about what happens when both sides of this relationship actually understand the chemistry, because it changes things for everybody. Let's start with the one that probably generates the most unnecessary invoices in this industry. The sand. Your pool guy tells you the sand needs changing. He says it every two to three years pretty reliably, maybe at an opening, maybe during a service visit. The number's consistent, two to three years. And look, he believes it. He's not trying to sell you something he doesn't think you need.

He was told two to three years by the person who trained him, who was told two to three years by the person who trained them, and somewhere at the bottom of that chain is a filter media manufacturer who figured out that a two year replacement cycle is a lot better for business than a twenty year one. Here's the thing about the material we're actually talking about. Quartz, which is what standard pool filter sand is made of, sits at a seven on the Moe's hardness scale. Your fingernail is a two. A steel file is a six and a half. Quartz is harder than both of them. It was formed over millions of years of geological pressure, compressed and fractured and eroded by forces that make a residential pool pump look like a ceiling fan on its lowest setting.

And the recommendation is to swap it out every couple of years? I also use crushed volcanic media on my pools as an alternative to standard sand. And I will point out that volcanic media survived an actual volcano. Temperatures in the thousands of degrees, pressures that reshaped the surface of the earth, explosive forces that sent materials miles into the atmosphere. And the concern is that a little bit of algae is gonna get it? Now, to be fair, filter media does fail. It's not indestructible, but when it fails, it fails in specific, measurable ways that have nothing to do with how old it is, and everything to do with how well the water chemistry is being managed.

Channeling is one. That is where water finds the path of least resistance through the media bed and bypasses filtration. You get flow, but you do not get filtration. And it shows up in the pressure differential. The spread between your filter's clean pressure reading and its dirty pressure reading, it narrows when channeling is occurring. That is something you can measure. It's not something that happens on a calendar. Biological fouling is another. Biofilm builds up in the media and filtration degrades. Shows up as clarity problems that you don't clear with backwashing. Also measurable. And then there's calcification, which is calcium deposits cementing the grains together and reducing effective surface area.

And here's the thing about calcification. It's a water chemistry problem. It's an LSI problem. Fix the water balance and you prevent it. That's a chemistry call, not a filter call. Every one of those conditions has a solution that does not equal replacement of the filter media. The solution is enzymes. A proper enzyme treatment with concentrated product forced through the media bed rather than just sitting on top of it. It breaks down the biological material and oils that conventional backwashing can't reach. Done correctly, the media comes back. I have filter media in pools on my route right now that has been in place for years and years and is performing at full spec.

Not luck, maintained water chemistry and condition-based enzyme treatments are what does it. Properly maintained filter media does not have a two to three year lifespan. It has a ten to twenty year lifespan, or maybe even longer. The sand doesn't know what year it is. What it knows is whether the water running through it is balanced or aggressive, whether the biofilm is being cleared or allowed to accumulate, whether someone is paying attention to the pressure differential or just waiting for the next scheduled replacement. If you are a pool professional listening to this, you now have the reasoning to do it differently. When a client asks why the sand doesn't need changing, you can tell them exactly why.

That is a different conversation than not yet. It's a conversation that builds trust and frankly saves your client real money, which they will remember. And if you're a pool owner, here's the question worth asking. Not does it need changing, but what's the pressure differential doing? A pool guy who has an answer to that is paying attention to the right things. The sand does not know what year it is. Replace it when it needs it, not when the sales cycle says so.

The next one is about a habit so embedded in this industry that most pool professionals don't even recognize it as a habit. It feels like expertise. It presents like a system. A prescriptive dosing. Two pounds of shock per week, twenty-four ounces of acid every week, a pound of alkalinity increaser every month, fixed amounts, fixed schedules, repeat until further notice. The pool store handed your pool guy this system. The manufacturer rep reinforced it, and it works often enough, most pools stay mostly clear most of the time, that there was never a strong reason to question it. Mostly is a word that hides a lot of damage. Here's the actual problem.

Your pool is not the same pool it was last week. The bather load changed, the temperature changed, it rained, or it didn't rain. The sun was out for six hours or twelve hours. Your salt cell ran at sixty percent or eighty percent. A kid dropped a sunscreen bottle in the deep end and half of it squirted out before anyone noticed. Every one of those variables affects what your water needs right now, and not one of them cares about the schedule on that instruction sheet. Two pounds of shock per week is not a chemistry decision. It's a guess expressed in units. We covered the 7.5% rule in episode two.

If you haven't heard that one, go back and listen. The short version is this your chlorine is a ratio, not a number. Free chlorine has to stay at or above seven point five percent of your cyanuric acid at all times. That ratio tells you exactly what the water needs, not the schedule, not the instruction sheet, the water. Same logic applies to acid. Twenty-four ounces a week to keep your pH in range is not a chemistry decision, it's a ritual. It might work on a pool with a perfectly predictable pH rise from week to week, but change the aeration, the bather load, the alkalinity, the temperature, and that twenty four ounces is either too much or too little.

Most often it's too much. Acid added in excess of what the water needs doesn't just disappear, it suppresses pH below target. It drives your LSI negative, it makes the water aggressive towards surfaces and equipment. Then, next week the pH climbs again and you add twenty-four more ounces, and the cycle continues. That's not managing pH, that's oscillating around it. Managing pH means testing it, knowing where your ceiling is, and adding the precise amount needed to bring it to target. Not the standard amount, the amount the water is asking for right now. The test kit is not a formality you run before grabbing the usual stuff out of the truck.

It is the decision. For the pool professional, chemistry-based dosing takes a little longer than grabbing the standard amounts, but it produces better outcomes, uses fewer chemicals, and gives you a real answer when a client asks you why you added what you added. That is the difference between a technician and a chemist. And the client feels that difference even when they cannot name it. For the pool owner, if your pool guy tests at the pool, does a little bit of math, and then reaches for the chemicals, let him do his work. That is the right sequence. If the chemicals come out of the truck before the test kit does, that's a conversation worth having.

Your pool is telling you what it needs every time you test it. Listen to it. Alright, next one. This is probably the most consequential thing on the list, and I want to spend a little extra time on it because the math is not complicated and the stakes are real. CYA cyanuric acid. The standard line is that CYA is fine up to a hundred parts per million. You'll hear this from pool stores, from pool guys, from manufacturing literature. It's stated with complete confidence, and it has been doing real damage to real pools for a long time. Here's the background. CYA is a stabilizer. It protects chlorine from UV degradation.

Without it, in an outdoor pool, direct sunlight chews through your free chlorine in a matter of hours. It has a real function and it earns its place in outdoor pool chemistry. Here's something the industry does not talk about much though. How cyaneric acid ended up in your pool in the first place. Trichlor tablets, the most convenient chlorine delivery product ever created, are approximately 57% active chlorine by weight. The remaining fraction is mostly cyanuric acid, baked in as a structural component of the manufacturing process. The industry didn't choose CYA as a stabilizer and then figure out how to put it in a tablet. It chose the tablet for convenience and got the CYA as part of the package.

Nobody at the time asked what happens when you dissolve hundreds of those tablets in a closed body of water season after season. The answer to that question is what we're talking about right now. But CYA does not evaporate. It does not degrade meaningfully under normal pool conditions. Every trichlorid tablet you dissolve, every single one, adds approximately forty two percent of its weight in cyanuric acid to your water all season long, season after season. The CYA stacks up. And as it stacks up, your effective chlorine drops, even if the free chlorine number looks fine in the isolation. Remember the ratio. At 100 ppm CYA, your minimum free chlorine floor is 7.5 parts per million.

You have to maintain 7.5 parts per million of free chlorine just to meet the minimum sanitization standard. That is a difficult number to hit consistently. That's also an expensive number to hold. And you are running as hard as you can just to stay even. My hard ceiling is fifty parts per million. I don't service a pool above that number without a plan to bring it down. And the plan is dilution, partial drain and refill. That's been the standard answer for a long time, and it's still the most reliable one. There is a method out there that has been getting some attention in the industry over the last few years.

A pool professional named Rudy Stankowitz developed a protocol using aluminum sulfate, the same alum product used as a flocculant, that has shown 25 to 50% reductions in CYA in field trials. Independent research from a firm called OnBalance corroborated the results in 2024. The mechanism is theorized to involve aluminum bonding with cyanurite and dropping out of the solution as a flock that you vacuum to waste. I want to be careful about how I frame this. The field results are real and the people reporting them are credible. But the chemistry behind why it works is still being debated. The reduction is partial, not complete. Results vary, and it has not been through the kind of formal validation process I would want before calling it a standard tool.

Some in the industry's scientific community are skeptical. That's not nothing. So where does that leave us? Dilution is the established proven method. The alum approach is worth watching, and some professionals are using it with reported success. I'm not ready to put it in the same sentence as a definitive answer. When the science catches up to the field results, I'll tell you. That's what this podcast is for. Your pool guy was handed the hundred part per million ceiling by the same system that handed him everything else. He was not wrong to trust it, but it traces back to product sales, not chemistry. Trichlor tabs are convenient. Pool stores sell stabilizer.

Nobody in the chain traced the accumulation back to what it actually does to chlorine efficacy. If you are a pool professional running pools with CYA above 50, you're working harder than you need to and spending more on chlorine than you should. Run the math on your worst pools. Episode two has the numbers. And if you are a pool owner who has been using trichlor tabs for a few seasons, ask your pool guy to test the CYA. Not as a gotcha, just as a starting point for a real conversation about the water actually needs. A pool guy who knows what to do with that number is the one that you want.

Alright, this next one, the training pipeline, handed your pool guy as a service. Bring in your sample, get it tested, find out what your pool needs. This one has a backstory that explains a lot. Pool store water test was not developed as a chemistry service. It was developed as a retail traffic driver. Bring in your sample, get your results, walk out with a big bag of chemicals. That was the model. It worked beautifully as a sales mechanism. It was adopted so widely and repeatedly and so confidently that it became indistinguishable from legitimate chemistry practice. The sales tool became the standard, and the standard has been producing recommendations based on degraded samples ever since.

Because water chemistry changes the moment you collect the sample. Chlorine offgases continuously from the moment you cap the container. By the time your sample hits the counter, it has less free chlorine than your pool does. The reading is already wrong. PH shifts. Dissolved carbon dioxide leaves the sample the same way it leaves your pool by off gassing. As it leaves, the pH rises. The pH reading at the pool store reflects what happened to that sample during a car ride in a warm vehicle. Not what your water was doing at the surface of your pool. And temperature changes. Temperature affects everything. LSI, chlorine effectiveness, saturation levels. The sample is at room temperature by the time it gets tested.

Your pool's not room temperature. What the pool store is testing is a ghost of your water, a snapshot that began changing the moment you took it. And they are making product recommendations based on that ghost. On-site testing at the pool with a quality digital or drop test kit at actual water temperature in real time. That's the only way to get an accurate picture of what the water's doing. For the pool professional, pulling out a Taylor K 2006 kit and running numbers at the pool is visible competence. Clients notice. They may not know exactly what you're doing, but they know you're doing something more careful than dropping a strip in a cup.

That matters more than you might think. And for the pool owner, if your pool guy tests at the pool on every visit, that's the right habit. If he is relying primarily on samples brought to a store, it's worth a conversation. Not a confrontation, just a question about how he handles on-site testing. A good pool guy will have a real answer. Test at the pool every time.

Okay, here's the last one. This one is subtle, and subtlety is the whole point. High pH is caused by too much alkalinity. Now, total alkalinity and pH are related, that's true. Alkalinity is the buffer that resists pH change. Higher alkalinity makes pH harder to move in either direction. The relationship is real and the chemistry behind it is legitimate. But here's where the conventional wisdom goes sideways. High alkalinity does not cause high pH. What high alkalinity does is make high pH harder to correct once it gets there. Those are different things, and if you mix them up, you end up chasing the wrong number. The actual cause of rising pH in most pools is CO2 off gassing.

Your pool water contains dissolved carbon dioxide. As that CO2 leaves the water, which it does continuously whenever water contacts air, the carbonic acid it was forming disappears with it, and pH climbs. This is a physics phenomenon that has been understood since 1803. It happens every day in every pool, regardless of what you add to it. High alkalinity makes the rise harder to correct. It did not cause the rise. Why does the distinction matter? Because if you believe high alkalinity is causing a pH problem, you chase alkalinity down trying to fix it. And then you create a new problem. Low alkalinity. It destabilizes water balance in a completely different direction.

You have not solved the pH problem. You've just added an alkalinity problem to it. If you're a pool professional who's ever had a pool where the pH keeps climbing no matter what you do, and you've been cutting alkalinity trying to get ahead of it, that's why it's not working. You're pulling the wrong lever. Episode six next week gives you the right one. And if you're a pool owner who has heard that high pH is an alkalinity problem, your pool guy is not wrong that they are connected. But the cause and the correction are more specific than that. Next Tuesday is worth a listen before your next service visit.

There's a full episode on this coming next week, episode six, the pH ceiling. I don't want to get too far into it because it deserves the full treatment. But the short version is this your pH has a ceiling. That ceiling is set by your carbonate alkalinity and your water temperature. Once you understand the ceiling, the rising pH stops being a mystery and starts being something you can actually anticipate. Chasing alkalinity to fix pH is the wrong lever. Understanding the ceiling is the right one.

So is your pool guy full of crap? Honestly, on some of those five things, probably yes. Not all five? Maybe. Not on purpose? Almost certainly. But on some of them, the information he's working with is not supported by the chemistry, and it's costing you money and over time possibly costing your pool surfaces and equipment. That part is true, and I'm not gonna soften it. But here's what is also true. The guy who told you those things was handed them by the person who trained him, who got them from the person before that, in a chain that goes back to a pool store training manual or a manufacturer rep or a shortcut because explaining the chemistry takes longer than loading the truck.

He repeated them with confidence because everyone around him said them with confidence and nobody along the way ran the numbers. That's not an excuse. Wrong information costs real money and causes real damage. The outcome does not improve because the intent was good. But it is an explanation, and the explanation changes what you do with it. If your pool guy is giving you bad information because he's being dishonest, you find someone who's not. That's a simple problem with a simple solution. But if your pool guy is giving you bad information because the system that trained him handed him incomplete conclusions with no reasoning attached, that is a structural problem.

And the solution is not a lower opinion of pool guys, it's a higher floor. Better information available to more people, pool professionals willing to hold what they were taught up to the light and ask whether it holds. Pool owners with enough background to have a real conversation when something doesn't add up. I want to say something directly to the pool professional listening to this episode. You run a route, you show up in the heat that most people will not work in. You manage chemistry on pools that do not cooperate for customers who sometimes make the job harder without even realizing it. You do all of that with whatever tools the training pipeline gave you, and in most cases, you're doing a better job than the forum posts gives you credit for.

This podcast exists in part because of you, not to replace you, to give you what the system did not, the reasoning behind the conclusions, the chemistry behind the recommendations, the language to explain to a client not just what you did, but why it works. A pool professional who understands why the CYA ceiling is fifty parts per million is not just doing better chemistry. He's having a different conversation with every client on his route. The homeowner who understands what good chemistry management looks like, doesn't shop on price. They call you back every season, they refer their neighbors, they trust you with the decisions instead of second guessing them.

That relationship gets built one visit at a time by someone who knows what he is doing and can explain why. And to the pool owner, the pool professional who shows up and does his job well is worth holding on to. The information gap we talked about today is not permanent. It closes every time someone in this industry decides to learn the reasoning instead of just repeating the conclusion. When your pool guy knows the pressure differential before he opens the filter lid, when he tests at the pool instead of handing you a sample cup, when he tells you your CYA is at 45 and here's what that means, that's not a coincidence.

That's someone who did the work. Those people exist. If you have one, the relationship is worth investing in. That's the defense. Your pool guy is probably passing on some things the system got wrong. He's probably not lying to you. He's doing his best with what he was given. And what he was given was not always good enough. We're working on that.

One more thing before I go. If your pool guy tells you the sand needs changing and it's only been 18 months, ask him what the pressure differential is doing. If he knows the answer, you have a good pool guy. If he doesn't know what the pressure differential is, call us. And if you're a pool professional listening, I want to be clear about something. This episode was not written to make you look bad. It was written to give you something the training pipeline did not. And every one of those five things has better information behind it than what you were handed. You can learn it, you can apply it.

And when you do, the pools are better, the clients trust you more, and the conversation changes. Come find us at poolsscientific.com. The resources are there, the episodes are there. If you have questions, reach out. There's a whole page called Ask Me On where I answer all your questions. We're building something here, and it's meant to include you. Pool professionals with the reason. Pool owners who can recognize it when they see it. Both of them having a better conversation than most of this industry is having right now. That is the goal. New episodes every Tuesday. Show notes and full resources at PoolsScientific.com. Find us on Spotify.

Next week, we go back to the chemistry, and I want to leave you with a question before we get there. You added acid last Tuesday, page was perfect. Came back Thursday and it was 7.8. You added some more acid again. Came back the following Tuesday, it was 7.9. Why does this keep happening? The answer has nothing to do with how much acid you're adding or how carefully you're testing. It has to do with physics. Specifically, a principle of physical chemistry first described in 1803 that governs every body of water on Earth, including your pool. Episode 6, Ph.D. See you next Tuesday.

This is the Pools Scientific Podcast.