Which of the following is NOT a method of controlling pool algae?

Reducing filter pump operation time is not a method for controlling pool algae because effective filtration and circulation are crucial in maintaining pool water clarity and preventing algae growth. The filter plays a significant role in removing debris and contaminants that can serve as nutrients for algae. When the filter pump operates for less time, it can lead to stagnant water areas, allowing algae to thrive.

In contrast, regularly brushing pool walls helps to disrupt the algae's attachment to surfaces, making it easier for the filtration system to remove them. Balancing pool chemicals ensures that sanitizer levels are adequate to inhibit algae growth, while shocking the pool with chlorine provides a high level of sanitizer to kill existing algae and prevent its recurrence. Together, these methods promote a clean and safe swimming environment.