+1. The industry is obsessed with algae because that's all anyone cares about. If the pool is clear, it must be sanitary, right ?
So many pool store (and now Amazon/Costco/etc) products contain copper because it's an algae inhibitor. It does pretty well preventing algae, at the expense of the pool finish and swimmers eventually turning green. But it's only a preventer. It does zero once you have algae.
Copper also isnt a contact killer so any swimmer to swimmer transmissions, bacteria, viruses, pathogens, etc have time to fester. So many products piggyback by adding silver too, which does sanitize, but usually not at the levels it's being added. And when it is at the proper levels, it takes a long time to work, so it doesn't even really do what it's supposed to do.
Avoid any magic products or anything with 'blue' in the title (industry code for copper)