In a spa usage scenario, what common issue might arise from high bather loads while the spa is in operation?

High bather loads in a spa can lead to skin irritation due to the introduction of various contaminants from the body, such as sweat, oils, and personal care products, into the water. When there are more bathers in the spa, the volume of organic matter increases, and if the water is not properly sanitized and balanced, this can lead to an uncomfortable experience for users.

Skin irritation often presents as redness, itchiness, or rashes, which are commonly associated with issues such as improper pH levels or inadequate sanitation. High bather loads can overwhelm the existing sanitation system, especially if the spa is not designed to handle the number of bathers present, leading to these undesirable effects.

In contrast, the other options wouldn't typically arise from high bather loads. Increased water clarity and improved chemical balance would suggest a well-maintained system rather than one under stress from excessive usage. Low filtration rates may occur, but this is typically a result of system design or operational issues rather than being a direct outcome of high bather loads alone.