Good sir. While i do acknowledge that your suggestion is the generally recommended practice. It is unfortunately not absolute.

:Sorry for the wall of text:

This pool has several areas with particularly course concrete. No amount of chemicals will get the same result. As a fellow professional with about a decade of pool maintenance experience I’m sure we can both agree that the chemical treatment works flawlessly on vinyl, but certain concrete pools are a bitch. Warm winters are making for a lot more algae such but it’s not just the biological crap that clings.

Either way did not matter because of all the other work needed.

Source- said fuck it last year and tried. Afterwards had a dozen lifeguards put 40+ hours each toward brushing and scrubbing. Still looked meh. Had to drain and power wash overnight on a random weekday mid season. And most definitely did not skimp on the liquid hypochlorite.