Hazy water - how much shock?

[drband]

10000 gal IG vinyl liner, sand filter BBB

FC 19.5 raised it to this level this morning
previously FC 9
CC <.5
TC 20 ish
pH 7.5
TA 130
CA 140
CYA 90
Temp 84
My question is... have I raised the FC high enough for shocking w/ a CYA of 90? The haze is improving a bit, but I want to make sure I get rid of whatever is causing it (algae or whatever).

By the way, this is the first time my water has NOT been crystal clear in over 1 Year (when I converted to BBB).

Looking at Ben's Best Guess chart, FC of 20 might be high enough, but I'm almost at CYA 100 which suggests shocking to FC 25. What do you guys think I need to do?