There could be various causes of cloudy water.

Let’s have a look at the WHYs… 

Poor water balance, including incorrect pH, alkalinity, or calcium hardness levels, can lead to cloudy water. High pH can cause scaling, while low pH can corrode pool surfaces. Improper alkalinity can lead to pH fluctuations, and low calcium hardness can cause water to become corrosive.

Poor filtration or circulation can result in suspended particles remaining in the water instead of being captured by the filter. This can occur if the filter is dirty, clogged, or undersized for the pool's volume.

Another issue could be the lack of sanitation. Low chlorine levels or ineffective sanitation can allow algae and bacteria to proliferate in the water, leading to cloudy water. Algae blooms can occur due to insufficient chlorine or poor circulation, especially in warmer temperatures or when organic debris accumulates.

Also, fine particles such as dust, pollen, or dead algae can remain suspended in the water if not filtered out effectively. These particles may be too small for the filter to capture, resulting in cloudy water. High Total Dissolved Solids (TDS): Accumulation of dissolved solids over time can contribute to cloudy water. TDS levels increase due to the addition of chemicals, evaporation, and water replacement without proper dilution.

How to Fix Cloudy Pool Water

Start by testing the pool water to assess pH, alkalinity, chlorine levels, and other parameters. Adjust levels as needed to ensure proper water balance. If chlorine levels are low or algae is present, shock the pool with a granular chlorine shock treatment to raise chlorine levels and kill algae and bacteria. Follow manufacturer instructions for dosage and application.

Also, you must ensure the pool pump and filter are running continuously to maximise water circulation and filtration. Backwash or clean the filter if it's dirty or clogged to improve filtration efficiency. Clean all skimmer baskets and a filter strainer as well. 

Brushing is essential in order to keep the pool clean. Brush the pool walls and floor to loosen any algae or debris clinging to surfaces, then vacuum the pool to remove the particles. Focus on areas with visible algae growth or sediment accumulation. If there is enough water in your pool, you can choose to vacuum to waste.

In some cases, you should consider using a pool clarifier or flocculant to coagulate small particles into larger clumps that can be easily filtered out. Follow product instructions for dosage and application.

If total dissolved solids (TDS) levels are high, consider partially draining and refilling the pool to dilute dissolved solids and improve water quality. Monitor TDS levels regularly to prevent excessive buildup.

Once you finally manage to clear up the pool, it’s essential to keep it in good shape year-round. Prevention is truly essential - therefore, establish a regular maintenance routine that includes proper water testing, chemical balancing, filtration, and cleaning to prevent cloudy water issues from recurring. Implement measures to prevent algae growth, such as maintaining proper chlorine levels, regular brushing and vacuuming, adequate circulation, and using algaecides when necessary. If unsure, just hire a professional service to take care of it.