Ok. I get the correlation numerically between CYA, CC, and FC. I get it the the CYA keeps some chlorine from burning off in the sun.
My questions arehow does CYA do that and does it ever 'release' it? Or, does it always 'protect' the same chorine so that the remainder you add is free to work and/or burn off by the sun?
Then my question is : does the sun screened chlorine also sanitize the pool, or just the FC. And, if it doesn't, then WHY protect it with CYA? Why not have little to no CYA and keep the pool sanitized with less chorine?