Commonly known as pond scum or moss, filamentous algae form dense, tangled mats on the water’s surface. Growth typically begins along the pond bottom or edges before rising to the surface, buoyed by the oxygen produced during photosynthesis. While filamentous algae are a natural part of aquatic ecosystems, excessive growth can reduce oxygen levels, disrupt water flow, and interfere with recreation. Managing nutrient levels and promoting water circulation are key strategies for controlling its spread and maintaining a healthy pond or lake.