How High To Take Cl2 To Break Down Gunk

[chem geek]

I estimated 110 CYA because it took a little above the 100 mark till I could no longer see the dot.

I think you meant a little below the 100 mark since above that mark would be between 90 and 100 ppm. The marks go from high (100) at the bottom to low (30 or 20 depending on test kit) at the top.