What symptoms may indicate water quality issues in a pool?

The symptoms that indicate water quality issues in a pool include cloudy water, foul odors, and visible debris. Cloudy water can be a sign of various problems such as improper filtration, inadequate sanitizer levels, or the presence of organic contaminants. Foul odors often suggest issues with water sanitation or an imbalance in chemical levels, as unpleasant smells can arise when bacteria and algae proliferate. Visible debris can also point to poor water quality, indicating that the pool is not being properly maintained or cleaned, which can lead to health risks for swimmers.

Clear water and a pleasant odor typically indicate that the pool is well-maintained and balanced, so they do not signal water quality problems. Low attendance of swimmers doesn’t directly indicate water quality issues, as attendance can be influenced by many factors unrelated to the pool's condition. Strong chemical smells, while sometimes associated with over-chlorination, do not necessarily point to water quality issues in the same way that the symptoms identified in the correct answer do. In summary, the presence of cloudy water, foul odors, and visible debris are direct indicators of water quality concerns that require attention to ensure a safe and pleasant swimming environment.