Well you FC is a little high ... shock level for CYA of 55ppm is a FC level of about 22ppm.
Just keep the FC > 22ppm and continue to brush and backwash. You can stop the shock process when you pass the 3 tests:
1. Water is clear
2. CC < 0.5
3. OCLT: lose no more than 1ppm FC overnight
Just keep the FC > 22ppm and continue to brush and backwash. You can stop the shock process when you pass the 3 tests:
1. Water is clear
2. CC < 0.5
3. OCLT: lose no more than 1ppm FC overnight