Hello from Southern Indiana (Louisville KY area). I'm new to the forum. If I've got this set up right, most of the info about my pool is in my signature. This is my 3rd season opening pool - my first pool. Replaced liner first season so its just a couple years old. Had no problems opening last year. This year had tons of algae in pool and it took lots of chemicals and vacuuming to get it cleaned up. Now the water is clear, pool is clean, but has 0 free chlorine. Chlorinator seems to be working normally. Total chlorine is 4.1, CYA is 19. My local store did some kind of extended analysis on my water that says I need 49 bags of shock - that my water has some kind of issue with bacteria consuming all the chlorine and they are recommending draining the pool significantly, adding fresh water and testing again. Does any of this make sense?