Which environmental condition can promote algae growth?

High sunlight exposure is a key environmental condition that promotes algae growth. Algae require sunlight for photosynthesis, which is the process they use to convert light energy into chemical energy. When a pool is exposed to direct sunlight, the warm and light conditions create an ideal environment for algae spores to thrive and multiply.

In contrast, cool temperatures can inhibit algae growth, as these lower temperatures do not support the optimal metabolic functions required for algae to flourish. Excessive rain can cause dilution in pool chemicals and may lead to increased debris and nutrients entering the pool, but it does not directly provide the conditions that would encourage algae like sunlight does. Windy weather can help to circulate pool water and potentially disperse algae, but it does not create an environment conducive to their growth.

Therefore, high sunlight exposure is the most significant factor listed that directly fuels the growth of algae in pool environments.