You want to raise the FC level as slowly as possible after an AA treatment. Preferably you should only raise FC by 1 ppm per day (i.e. target of 1 today, target of 2 tomorrow). Raising FC too quickly can result in the stains returning.
It is very common for it to take a lot of chlorine to register any FC level at all. AA and chlorine destroy each other, so you have to burn of any remaining AA before you will be able to maintain an FC level.
It is also normal for the PH to be low after a treatment. You should raise the PH fairly slowly, for now raise it enough so that it shows up on the test as something above the lowest possible reading, but not much more than that. Then raise it by no more than 0.1 each day until you get back to the low end of your normal range.
It is very common for it to take a lot of chlorine to register any FC level at all. AA and chlorine destroy each other, so you have to burn of any remaining AA before you will be able to maintain an FC level.
It is also normal for the PH to be low after a treatment. You should raise the PH fairly slowly, for now raise it enough so that it shows up on the test as something above the lowest possible reading, but not much more than that. Then raise it by no more than 0.1 each day until you get back to the low end of your normal range.