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 you manage your pool.

• Why contact time governs filtration efficiency — and what that means for pump sizing
• What total dynamic head is and why it’s the only legitimate reason to upsize a pump
• The Pools Scientific dynamic flow audit — what it measures and what it finds
• Algae taxonomy: green, yellow, black, and pink — four organisms that require four different approaches
• Why algaecide as a primary treatment is the wrong first response to a green pool
• Why the correct word for what algaecide actually does is Algestat
• The HOCl dissociation curve and why the same free chlorine number means completely different things at different pH levels
• Why the 7.4 to 7.6 pH target is tighter than the industry standard — and why that matters

• Episode 2: The 7.5% Rule — Free chlorine minimum relative to CYA, covered in full
• Episode 3: LSI Explained — Saturation index and the six variables that govern water balance
• Episode 6: The pH Ceiling — Henry’s Law and why pH keeps climbing in salt pools
• Ask John: poolsscientific.com/ask-john — Submit your pool chemistry question