There could be various reasons for the water turning cloudy or murky. Check if your circulation system is operating correctly.
If there is something stuck in the pool filter, it will be unable to remove the contaminants properly. Sometimes, ammonia may be the cause; so, you may want to add chlorine to the pool.
Or, maybe the chemicals are imbalanced. Test the water chemistry and balance the pH, free chlorine, calcium hardness, and TA levels.
Cloudy water is also an indication of algae build-up or excess foreign particles. In such cases, a pool flocculant is the best way to drag all those particles to the bottom, which you can later vacuum.