The Pools Scientific Podcast

Your hot tub is not a small pool, and treating it like one is where most of the trouble starts.  In this episode, John walks through why a tub is a different animal: more bathers per gallon, water held at 104 degrees Fahrenheit (40 degrees Celsius), and nowhere for anything to go.  We cover bromine vs chlorine and how to choose, why dichlor, the jar most pool stores hand you for a spa, quietly bui...

Winter pool maintenance is where most pool damage starts, and almost nobody does it.  Once the cover goes on, the water sits against the plaster, gelcoat, or vinyl liner for about six months, and cold water changes the chemistry in ways the summer rules don’t cover.  John walks through what happens under the cover, why winter pool chemistry runs on the LSI instead of the in season numbers, and wha...

Pool plaster mottling is one of the most common complaints in new pool construction, and the industry's standard explanation, installer error or bad water chemistry, is usually wrong.  The real cause is calcium hydroxide migration during cement cure, and it has been a solved problem in commercial concrete construction since the 1950s. The pool industry just never picked it up. This episode co...

Pool plaster mottling gets blamed on your water chemistry almost every time. This episode asks a different question.  What if the uneven gray discoloration was decided before the pool ever held a drop of water?  We get into the science of new pool plaster problems, and what pool plaster warranty coverage actually protects you from, and what it does not.  If your plaster is showing discoloration an...

Pool metal stains rarely come from just one source, and this episode walks through the real chemistry behind them.  John covers where metals and minerals actually enter pool water, why iron, manganese, and copper stain differently, and why calcium and magnesium follow the same solubility rules everyone assumes are unique to metals.  He breaks down the difference between a sequestrant and a chelato...

Closing day is the last time anyone touches your pool's chemistry until spring, and most closing checklists skip the one thing that actually matters: what happens to that water for the next five months.  This episode covers pool closing chemistry by pool type, since winterizing an above ground pool, winterizing an inground pool, vinyl liner pool winterizing, fiberglass pool closing, and plast...

Why does that sharp chemical smell at the pool mean your chlorine is losing, not winning?  This episode breaks down the real chemistry behind combined chlorine and chloramines, the actual mechanism behind the seven and a half percent chlorine-to-cyanuric-acid ratio, and why a fixed LSI range can turn against your pool's plaster and equipment without warning.  Includes a real two-year, zero-CY...

Eight real questions this episode, pulled from the Ask John page, the Trouble Free Pool forums, and real clients of the Pools Scientific field lab.  Every one of them starts the same way: a reading, a calculator, or a manufacturer spec that looks correct and still leads somewhere wrong.  - A plaster pool with a near-perfect LSI still growing scale.  - A salt cell manual that flatly contradicts thi...

Twenty episodes in, this one is different.  Not a new chemistry lesson, a release.  Every dreaded test result, every answer taken on faith from a stranger, every quiet moment of not knowing, all of it gets named directly, and then set down for good.  This episode looks back at everything actually built along the way, not just the chemistry, but the confidence to trust it, and asks a question most...

Above ground pools, vinyl liners, and fiberglass shells all get treated like the industry's afterthoughts, but the actual chemistry never agreed to that hierarchy.  This episode walks through above ground pool chemistry, including why cyanuric acid protects an above ground pool exactly as much as any gunite pool, the real reasoning behind calcium hardness targets in a vinyl pool, and the hone...

A real member's pool, followed across five real water tests over nearly three months.  Every single time, a retail pool store gave the same handful of generic recommendations, and every single time, the real answer was something else entirely.  This episode walks the whole case file in order: a chlorine reading roughly a hundred and forty times higher than the pool needed, a crash to zero, a...

Ten products sit on every pool store shelf with almost no real explanation attached: borates, enzymes, non-chlorine shock, chlorine neutralizers, clarifiers, flocculants, mineral and ionizer systems, scale control, defoamers, and phosphate removers.  This episode goes through each one with the actual chemistry, what it is, what it does, and when it earns a place in your pool, no gimmicks, no shopp...

Test strips, drop titration, photometric readers, digital salt meters, TDS probes, automated monitors, even your thermometer.  Every real type of pool test kit, not sponsored or promoted, explained with the honest pros and cons of each, so you can pick the one that actually fits how you test.  Then a real world comparison: five different kits, one pool, wildly different numbers, and the actual rea...

 A health inspector failed a pool that had nothing wrong with it, for having too much chlorine.  What actually happened next traces back through a hundred years of pool chlorine history, a cyanuric acid relationship most codes get wrong, and a real arithmetic error sitting inside a real municipal pool code.  Full citations, both code excerpts, and the chemistry sources are in the show notes at poo...

 Every pool runs on the same hydraulic loop, suction, pump, filter, and returns, and almost nobody who owns one has ever had it explained.  John Cooper walks through the real physics behind pump cavitation, why turning a pump up rarely fixes a dead spot, and how a simple piece of equipment most pool owners have never heard of uses pure physics to protect a cartridge filter.  From there, the same w...

Your pool can test high on free chlorine and still turn green.  This episode walks through the full life cycle of a pool algae bloom, how it stays dormant for weeks, why it seems to appear overnight, and what actually happens at the cellular level when it dies.  We cover all four types you'll actually run into, green, mustard, black, and pink slime, plus the real chemistry behind the cyanuric...

Shock has become the answer to every pool problem, which is the first sign nobody's actually answering the question. There's exactly one chemistry accurate definition of shocking a pool: achieving breakpoint chlorination. Everything else calling itself shock is borrowing a word it was never entitled to. This episode traces the industry's 10X shock rule back to where it actually came...

If your pool smells like chlorine and your eyes are stinging, you've probably heard the same explanation everybody hears: too much chlorine.  That answer is backwards. In this episode, John Cooper breaks down what's actually happening in that water. Free chlorine reacts with the nitrogen everyone brings into a pool (sweat, saliva, sunscreen, and yes, urine) to form chloramines. There are...

A short, straight answer to what the Chemist's Circle is, what it costs, and why it exists. Two personalized chemistry submissions a month, a real response within twenty four hours, written for your pool, not a general answer. Plus the founding rate, the one thing this week's episode doesn't say on air, locked in permanently for as long as you stay a member. The first hundred people...

This week, John answers real questions from real listeners. No filler. Plus the first-ever So What? segment, and a check-in with Warren Bell, three weeks after we first told his story. Contributors to this episode: Mark Yancey U/Barnacle_Meat, from the swimmingpools subreddit Alec Wasserman U/Striking_Manner9380, from the swimmingpools subreddit U/wankertank, from the pools subreddit Warren Bell W...

This one's different from every episode before it. Episode 10 is the origin story. All of it. A strawberry farm in Missouri. A submarine. Twenty five years of homebuilding. And a swimming pool route in Kansas City that none of it would have led to on its own. I'm not going to tell you more than that here. Some of this episode is funny. Most of it isn't. It's the most personal e...

The pool industry has been repeating the same rules for decades. Bigger pump. Add algaecide. Keep pH between 7.2 and 7.8. Most pool owners follow those rules without question. Most pool professionals teach them without question. This episode asks why. Three rules. Three real mechanisms. Three cases where the answer you were given is the simplified version, and the complete answer would change how...

Every pool professional has one. A pool that breaks the rules. The chemistry looks right. The equipment runs fine. And the water still does something it shouldn't. This episode is about what to do when the obvious answer isn't there. John Cooper walks through the diagnostic framework he uses when a pool stops making sense, built from years of working pools that refused to cooperate and s...

Every week there's a new product promising to replace pool chemistry with something simpler. One pod. One scoop. One treatment. The testimonials say it worked. The price says it's worth trying. This episode is not about mocking the people who bought them. It's about what the chemistry actually says. Because the chemistry doesn't care about the label, the view count, or how conv...

You add acid. pH comes back up. You add more. Eventually you grab the whole jug. Then you pull up the next morning and the liner is wrinkled — across the walls and floor in that specific way that only happens one way. This episode explains why that happens. Not with a product recommendation. Not with a different test kit. With the physics that's been governing dissolved gases in liquids since...