Photo showing a realistic, moulded artificial fibreglass waterfall (polyresin), with fake grey stones edging the cascade of water. As the water runs into the pond, green algae begins to form on the grey plastic waterfall, making it appear more natural and real, particularly when it is softened with dense planting at the sides, such as prostrate junipers / conifers. Many pond owners choose to grow watercress in waterfalls, to help reduce nitrates within the water and improve the overall water quality in the pond.