We used Cutrine granuals, it does come in liquid though, but that just seemed like pissing in the ocean though to me. CS is cheaper, but also has warning labels about swimming after application, so we went with Cutrene.  We recharge our lake early with dye and that is the medicine. If you wait until June or July, it is too late. Our water is pretty blue, most folks ask where the palm trees are when they ski there the first time. We add acid blue #9 dye and Acid yellow #23 aka Tartrazine . They work on different ends of the ultraviolet spectrum for blocking sun. Use 10:1 blue to yellow ratio. We also added about 50 Amurs over the years, maybe 10 died off intially, so about 40 left. Some are getting pretty big, over 2 feet long. Lake is 18 feet deep, about 2000 feet long, and average about 400feet wide, narrow at one end and over 700' at the other. Butler chemical carries the dyes in powder form. I think for a lake our size, we used 25kg of blue and 5 kg of yellow for the intial charge. Each year we add about half of that early in the season. Inital cost is somewhere around $800 if I remember. Where rubber gloves and long sleeve shirts, the powder gets all over your if not careful. The best is to mix it with water on a calm day in a controlled environment.  http://sphotos.ak.fbcdn.net/hphotos-ak-snc3/hs100.snc3/16731_331234525537_672250537_9511863_4971625_n.jpg