Diver,
Your father in law might know CYA as stabilizer. Maybe.
Several decades ago I knew a family with an in-ground pool. I swam in that pool every summer for 15 years. Every year they opened that pool with dozens of jugs of Clorox and vigorous cleaning. They used floaters with tabs, and if ever things (rarely) got out of hand, the pool was given the multiple jugs of Clorox treatment. Everyone vacuumed; the pool looked clean always.
I don't recall ever seeing any sort of test kit. Luckily, no one got sick; nothing bad happened. They never bought anything from the pool store except for those floater tabs.
Maybe your father is a bit like these old friends of my parents. Some people want to know more; others couldn't care less.
Pool School states a simple fact quite simply. I don't know where better to refer you to. You enjoy your Trouble Free Pool! :-D
Lana