What causes alge blooms in ponds?

Algal blooms in ponds are caused by an excessive growth of algae, which are microscopic plants that live in water. Algal blooms can occur naturally, but they are often caused by human activities that add nutrients to the water, such as fertilizers from farms and lawns, sewage, and animal waste. These nutrients provide the algae with the food they need to grow rapidly, leading to an algal bloom. Algal blooms can be harmful to the pond ecosystem, as they can block sunlight from reaching other plants and animals, reduce oxygen levels in the water, and produce toxins that can be harmful to humans and animals.