Algae Control by BIOTEC controls dirty-looking filamentous/hairy/cotton algae and suspended pea-soupy green water. It does this by disrupting photosynthesis over 3 – 10 days. Clears tanks and ponds. For pond edge algae, apply at the edges of the pond. When algae is dying, stop applying algaecide. Overdose may harm aquatic plants & stress fish. Do not use on fish intended for human consumption.