My question is should I shock if I have any combined chlorine? Is there a time when a shock is needed for maintenance purposes? Is there a specifc level of cholrine needed so there will never be any CC?

I have a 20K IG plaster finish pool. I maintain around 4ppm Chlorine by way of a SWG.

Water is clear. No noticible problems. Only users are two adults. Pool is in direct sun all day (central FL). No enclosure.

TC = 4
FC = 3.5
CC = .5
ALK = 100
CA = 220
CYA = 40
PH = 7.6
TEMP = 88

Thanks.