A 25% copper compound used for years as an algaecide. This product is effective against all forms of algae including: filamentous, planktonic, and branched algae. The crystal form is most effective on bottom mats while the fine crystal may be easily spread or dissolved in water. Copper sulfate is less effective in hard water than chelated copper products. This product is corrosive to metal equipment and toxic to fish in soft water. Normal application rate is 2.7 pounds per acre foot of water treated. Effective for control of swimmers itch with special application methods. No restrictions on water usage following application.