Which aspect contributes to high algal growth in aquariums or ponds?

Excess nitrate levels play a critical role in promoting high algal growth in aquariums or ponds. Nitrates are a form of nitrogen that serves as a nutrient for algae, particularly in aquatic environments. When there is a surplus of nitrates—often from uneaten fish food, fish waste, or decaying plant material—algae can thrive and proliferate rapidly.

While aquatic plants also require nitrates for growth, algae generally outcompete them in nutrient-rich environments, leading to algal blooms that can disrupt the ecosystem balance, deplete oxygen levels, and affect fish health by blocking light and altering water chemistry. Hence, effective management of nitrate concentrations is crucial for maintaining a healthy aquatic environment.

Other choices such as low light conditions, high phosphate levels, and short feeding intervals can influence algal growth; however, excess nitrate levels are particularly significant because they directly enhance the availability of nitrogen, which is often a limiting nutrient in aquatic systems.