You can determine your source strength - someone ( I think CarlD ) has a thread on it somewhere on the forum - you're a subscriber so you can search.
I don't really see why it matters. You need lots of FC as demonstrated by the fact that you have persistent CC readings: FC is being consumed reducing (oxidising) suff in your pool and showing up as CC.

Shock level for your CYA is 20, so add the dose of bleach you think you need, pump on 24/7, let it mix for an hour, measure FC if it's not above shock level, add more and adjust your dosing as necessary.

BBB for clearing a mess:
Bleach - Bleach - Bleach and Brush - Brush - Brush.