I just went through this and I know I might get bashed, but I added... flocculant. My water had been filtering for 2 weeks and I had been adding shock levels of Chlorine, but was still blue and cloudy. The floc worked and I vacuumed to waste. I had run out of DE for my sand filter and after purchasing more I have a crystal clear pool.

The pool mess was my own fault. I waited too long to cover in the Fall.