Lake Colorant WSP HP will maintain the natural beauty of water by turning it into an attractive, natural blue color. It works perfectly in small lakes, ponds, water hazards, and fountains. It is safe for swimming and other sports during and after treatment of this product. It can also be used as an aquatic spray pattern indicator. Just spray the weeds with this colorant and there will be a blue color mark to it. It is safe for fish and other aquatic animals when used as suggested.