Hey Victoria,
I’ve run into that before. Shocking kills the bacteria and algae, but it doesn’t automatically clear out all the tiny particles floating in the water. If your filter is clogged or hasn’t been cleaned in a while, those particles just keep circling around, leaving the water cloudy.
I’d recommend backwashing or cleaning your filter thoroughly, brushing the walls and floor, and running the pump longer than usual. If it’s still a bit hazy after that, adding a clarifier can help bind the fine debris so your filter can remove it more effectively. Usually within a day or two, the water clears up if you give it proper filtration and circulation.