How much liquid chlorine can I add at 1 time to kill ammonia in my pool ?

Had a phosphate problem as a result of algae in the pool over the winter. I killed all the phosphates, but I discovered I still was not getting a FC reading on the test strips. I found out I have VERY HIGH levels of ammonia in my pool ( 22,000 gallons ) - I realize I need about 20 gallons of 12.5% liquid chlorine to kill it - I've been putting in 3 gallons per night, so far 9 total - am I doing this right ?? Was I supposed to put ALL 20 gallons in at 1 time ? Am I still killing the ammonia with 3 gallons per night ? I was afraid of bleaching the vinal liner. Thoughts ??