In your pool, a half a gallon (2 quarts) will raise your cl a little more than 1ppm.

Ideally, FC and TC are equal which would mean that your CC reading is 0 which is what you want. FC + CC = TC. On your test kit, you should subtract TC - FC to find CC. TC should be the higher number or better yet, equal to FC. Thus, you should never get a negative number for CC.