For now I wouldn't worry about your TA levels. Only really worry about them when/if your pH hits around 7.8. Go ahead and add another 20oz of CYA using the sock method. This should raise you up around 40ish in which you should see a HUGE difference in the amount of chlorine you drop during the day.
As for the 242oz you added and the difference in how much your FC increased. Can you check the label of the bleach you are using for the strength? Is it labeled as 8% or 6% Sodium Hypochlorite? Using PoolMath and 13k gallons for your pool, 242oz of 6% Bleach would increase your FC level up only 9ppm.
As for the 242oz you added and the difference in how much your FC increased. Can you check the label of the bleach you are using for the strength? Is it labeled as 8% or 6% Sodium Hypochlorite? Using PoolMath and 13k gallons for your pool, 242oz of 6% Bleach would increase your FC level up only 9ppm.