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, your filter will be unable to remove the contaminants properly. Sometimes, ammonia may be the cause. If that is the case, you may want to add chlorine to the pool.
Another reason for your pool’s unusual look may be in result of the chemicals are imbalanced. You will need to 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.