I'm a newbie to pool maintenance, but I'm a chemical engineer. With that said, more out curiosity than anything else, I'd like to understand the behavior of CYA. I keep stumbling across posts that say if the CYA level gets too high you can't maintain adequate levels of free chlorine. However, if CYA only serves to chemically "tie-up" the chlorine and act sort of like an electrical capacitor by permitting slower release of the chlorine, then it seems logical to me you should be able to attain proper FC levels regardless of the CYA content. It's not like the CYA eats the chlorine and turns it into raw asparagus, it just holds it for slower release.
Why can't you say double the CYA level, have it "hold" double the chlorine and then establish a correct FC level? It seems it would merely provide a greater buffering capacity for chlorine and what's wrong with that?