shock at first sign of CC ?

[DavidD]

hi.

(1) i'm using ben's best guess, with a CYA of ~60.
so i know that means to always keep the FC at
5 ppm to 10 ppm.
should i shock (push FC up to 20) whenEVER i have any CC reading ?
or is it ok to let the CC build up a while.

I would generally shock if a CC reading was greater than .5 ppm.

(2) also, i assume that i push the existing FC up to 20, and do not simply
add 20ppm worth of chlorine. is this correct ?

As dawndenise clearly pointed out, you are correct

Dave