Yep, the goal is 0 CC. We say less than 0.5ppm CC because that is the resolution of the Taylor FAS-DPD test with a 10ml sample.

Are you adding bleach to get to 15ppm and then it drifts below? Perhaps you should dose enough so the FC is at least 15ppm the next time you test.

CC doesn't cause cloudiness, it's probably dead algae. Did you backwash because pressure went up 8-10? Dirty filters filter better, avoid backwashing before you have to.