New episodes every Tuesday.
One topic per episode, explained from first principles, with a full transcript on every episode page.
All episodes 28
What Else Could Possibly Go Wrong in Your Pool in Winter? Crystals, Ice, and Other Winter Surprises
Winter is hard on a pool, and not all of it is explained. This episode sorts what can go wrong under the cover into three piles: Known, Theory, and Shrug.
Hot Tub Chemistry: Bromine vs Chlorine and Why Your Hot Tub Isn’t Just a Small Pool
Your hot tub is not a small pool, and treating it like one is where most of the trouble starts.
Winter Pool Maintenance: What the Water Does to Your Pool Under the Cover
Winter pool maintenance is where most pool damage starts, and almost nobody does it.
Pool Plaster Mottling: Causes, Chemistry, and the Real Fix
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 Four-Year Lie: What Your Plaster Is Trying to Tell You
Pool plaster mottling gets blamed on your water chemistry almost every time. This episode asks a different question.
Metal Staining and the Ecosystem of Metals in Pool Water
Pool metal stains rarely come from just one source, and this episode walks through the real chemistry behind them.
Beyond the Pool Store
Why does that sharp chemical smell at the pool mean your chlorine is losing, not winning?
Ask John, Part 2 Why a Correct Reading Doesn’t Always Mean a Correct Answer
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.
Let That Stuff Go!
Twenty episodes in, this one is different.
Pool Chemistry: Is Every Pool the Same, or Is Every Pool Different?
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.
Pool Won't Hold Chlorine: Five Wrong Answers and the One That Worked
A real member's pool, followed across five real water tests over nearly three months.
Pool Additives: What Borates, Enzymes, Clarifiers, and Phosphate Removers Actually Do
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.
Too Much Chlorine in Your Pool? Why This High Reading Was Actually Correct
A health inspector failed a pool that had nothing wrong with it, for having too much chlorine.
Pool Circulation: Hydraulics, Thermodynamics, and the Machine Nobody Explains
Every pool runs on the same hydraulic loop, suction, pump, filter, and returns, and almost nobody who owns one has ever had it explained.
Pool Algae: What Actually Kills It (And Why You Probably Don't Need Algaecide)
Your pool can test high on free chlorine and still turn green.
The 10X Lie: Shocking Your Pool Isn't What You Think It Is
Shock has become the answer to every pool problem, which is the first sign nobody's actually answering the question.
Combined Chlorine and Chloramines: Why Your Pool Smells Like Chlorine When You Actually Need More of It
If your pool smells like chlorine and your eyes are stinging, you've probably heard the same explanation everybody hears: too much chlorine.
Ask John, Part 1 Real Pool Chemistry Questions, Real Answers
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.
From Strawberries to Submarines to Swimming Pools
This one's different from every episode before it.
But Why?
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.
The Pool That Made Me Feel Stupid: A Diagnostic Framework for Every Pool Problem That Doesn't Make Sense
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.
I Saw It On TikTok
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.
The pH Ceiling: Why Your pH Keeps Rising and What to Do About It
You add acid. pH comes back up. You add more. Eventually you grab the whole jug.
My Pool Guy Is Full of Crap
"My pool guy is full of crap."
Salt Chlorine Generators: The Best Chlorination Method Available. Here's Why It Still Fails.
Salt chlorine generators are, in my professional opinion, the best residential pool chlorination method available today. I recommend them. My company installs them. And they fail constantly.
LSI: The Number That Runs Every Pool
There is one calculation that determines whether your pool water is slowly destroying your equipment, etching your plaster, or quietly depositing scale on every surface it touches.
The 7.5% Rule. The Most Important Number You've Never Heard Of
Your test strip shows chlorine. The water looks clear. But is your chlorine actually working?
Why Pool Care Is a Science Problem
John got a call from another pool guy who was in way over his head.
Bonus episodes 3
Closing and Winterizing Your Pool
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.
Best Pool Test Kit: Which One Should You Actually Trust
Test strips, drop titration, photometric readers, digital salt meters, TDS probes, automated monitors, even your thermometer.
Stop Buying Pool Chemicals You Don't Need: The Chemist's Circle, Explained
A short, straight answer to what the Chemist's Circle is, what it costs, and why it exists.
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