Did you test the chlorine level? You just have to keep the chlorine at shock level for your pool - with a cya of 30 - 50, and a 7600 gal, you would need approx. 2 gallons of bleach to get to 15ppm - that is starting from 0 chlorine. It depends on when you added the chlorine, and if it was used up.
You can backwash if your filter has a backwash position on it. I don't know what kind of filter you have. Backwashing a position on the filter that lets you clean out the filter with water from the pool.