I used Crystal Plex from the feed store. Its a gallon jug. I poured it in my backpack sprayer and added another gallon of water. then spray the banks as well and surrounding algae. Any algae floating I spray as well. Try to cover the whole surface of the pond. It was $40 and after three days, the pond was clear. We use ours for swimming and it even eliminated the algae on the beach area about four foot below the surface.