The best way to apply liquid copper sulfate is to do a broadcast spray.  Spray the algae mats with Crystal Plex in sections.  You will only treat 1/3 to 1/2 of your pond at a time to prevent oxygen depletion.  See labeled instructions for application amounts and click here for how to measure. The algae will brown up within 48 hours. Copper Sulfate is toxic to Koi, goldfish and trout.