The problem with blanket weed is that once it starts to grow it is like garden weeds it keeps coming back! If you use detrimental chemicals to eradicate it, inevitably it returns! The best way to tackle the weed is to reduce its food sources so natural die back can take place, and further growth is stifled. Eco-Pure is designed to be added to the pond regularly to keep the growth low. With Eco-Pure it is possible to reduce growth and maintain the level at about 10 mm. Dosage: Use cup supplied in container, add 1 or 2 heaped cups (approx 40 gms per cup) per 1000 gallons of pond water, mix measured quantity into 1 gallon of pond water in a bucket. Stir, then apply around edge of pond area, once every week