Algae is a simple non-flowering plant that is part of a group that comprises seaweeds and other single-celled forms. It contains chlorophyll but lacks true vascular tissue, leaves, roots, and stems. The two main types of algae include string algae and suspended algae. In most cases, algae is not harmful to your water feature or pond. The plant is needed to absorb nitrates, which if left unchecked, can harm aquatic life. However, algae can also multiple extremely quickly and it often drives pond owners crazy. That's why Everything Koi carries a large selection of electronic algae control systems.