Dwest

While trying to balance the chemicals in our pool after it was shut down due an equipment failure the water turned cloudy and light blue. We ran the filter overnight and the filters were clogged with a cyan blue slime. The pool was clear before the incident. Ph was low, below 6.8. Free chlorine was not registering but total chlorine was high. I added Ph up using the recommended dosing. Later the same morning, we added a small dose of shock and that seemed to initiate the problem. Any ideas what happened?