Episode 5  ·  May 19, 2026
My Pool Guy Is Full of Crap
The Defense
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“My pool guy is full of crap.” It shows up in forums, in Facebook groups, in Reddit threads. And sometimes they’re not wrong.

But most of the time the pool guy isn’t the problem. The problem is what he was handed before he ever showed up at your pool. This episode is his defense.

The Five Things
01
Change Your Sand Every Two to Three Years
Quartz has a Mohs hardness of seven. Volcanic media survived an actual volcano. Neither has a two-year lifespan — and there is a better answer than replacement.
02
Add Two Pounds of Shock Per Week and You’ll Be Fine
Fixed amounts on a fixed schedule regardless of what the water actually needs. A guess expressed in units. Not chemistry.
03
Your CYA Is Fine Up to 100 ppm
The most consequential number the industry got wrong. CYA does not evaporate. It stacks up season after season and takes your effective chlorine with it.
04
Bring Me a Water Sample and I’ll Get It Tested
The sample starts changing the moment you collect it. What the pool store tests is a ghost of your water — and the recommendations follow from there.
05
High pH Is Caused by Too Much Alkalinity
High alkalinity makes pH harder to correct. It did not cause the rise. Chasing alkalinity to fix pH is the wrong lever.
What You’ll Take Away
  • Why the pool service training pipeline produces confident conclusions without the reasoning behind them
  • Why filter media failure is a condition-based decision — not a calendar decision
  • The difference between prescriptive dosing and chemistry-based dosing — and what it costs to confuse them
  • Why your CYA ceiling is 50 ppm and the only way to lower it is dilution
  • Why on-site testing is the only accurate testing — and what happens to a sample on the way to the store
  • The actual mechanism behind rising pH — and why Episode 6 is the full answer
Resources Mentioned
  • Episode 2: The 7.5% Rule — The Most Important Number You’ve Never Heard Of
  • Episode 3: LSI Explained — The Number That Runs Every Pool
  • Taylor K-2006 drop test kit — on-site testing standard referenced in Thing Four
Next Tuesday — Episode 6
The pH Ceiling
You added acid last Tuesday. pH was perfect. You came back Thursday and it was 7.8. Why does this keep happening? The answer has nothing to do with how much acid you’re adding. It has to do with physics — and a principle first described in 1803.
New episodes every Tuesday.
Find us on Apple Podcasts and Spotify. Show notes and resources at poolsscientific.com.