Episode 18: Pool Won't Hold Chlorine: Five Wrong Answers and the One That Worked | 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 builds cyanuric acid until the sanitizer stops doing its job, and what the CDC says about ...

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 what a pool closing kit leaves out. You’ll hear what causes plaster etching in winte...

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 covers the full mechanism: how Portland cement produces calcium hydroxide as a hydration byproduct,...

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 and mottling in the first few years, you are going to want to hear this one before y...

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 chelator, walks through a rare copper cyanurate case that took fifteen drain and refill cycles...