Is CL loss by percentage?

[Whatrymes]

Hey:

First opening with BBB, initial results (TF-100):
CL-0
pH-7.5
TA-60
CYA-40
CH-100

Water was very clear but there was a "dust" on the bottom so decided to shock. Added 11/2 gals 12.5%, added 4 lbs of baking soda.
CL-15
CC-0.5
pH-7.5
TA-90
etc.
Water is sparkling clear, everything seems well.
OCLT-1.0, CC-0.5

I'm just wondering about the speed that the CL fell. Normally, my CL loss never exceeds 4 ppm per day, but I was down from 15 to 6 in 12 hrs.
Normal?
Does CL dissipate by % as opposed to the same amount of points no matter what the initial reading is?

Thank you.

 

[JasonLion]

If everything else remains the same, the amount of chlorine you lose is a percentage of your starting level. With CYA around 40 your chlorine loss is completely normal.