Which of the following can lead to cloudy water in spas?

Cloudy water in spas can be attributed to increased dissolved solids. When the concentration of dissolved substances such as minerals, organic matter, or contaminants rises, it can affect the clarity of the water. High levels of dissolved solids can result from a combination of factors, including inadequate water exchange, improper filtration, or the introduction of various substances through bathers and spa additives. When these solids are present in excess, they scatter light and make the water appear cloudy, negatively impacting both visual quality and user experience.

Understanding the roles of other factors can be helpful in differentiating their effects on water clarity. For instance, excessive foaming can indicate high levels of soaps or surfactants, which can also contribute to cloudiness but primarily affect surface appearance rather than overall clarity. High water temperature can encourage the growth of algae or bacteria but is not a direct cause of cloudiness on its own. Low pH affects water balance and can lead to corrosion or scaling but does not directly lead to cloudiness; however, it can affect the effectiveness of sanitizers and clear water maintenance. Therefore, increased dissolved solids is the most direct and relevant factor that can lead to the occurrence of cloudy water in spas.