In your pool, 1/4 of a cup of 6% bleach will raise your cl by 1ppm. With a cya of 40, you should keep your cl between 3-6 all the time and your shock level will be 15. CC will NOT come down as FC does.

Have you used anything besides the dichlor to raise the cya? If not, I wouldn't worry about testing for it again for quite awhile. Maybe sometime in another month or so and maybe in the fall when you get ready to close the pool. The people who have to test for it frequently are those who are using trichlor tabs and dichlor powder to shock with.