2, prevention and control methods ① Sprinkle 50 kilograms of plant ash on the moss in the pond without fish, which can make the moss die without sunshine; The pond where fish have been put can be sprayed with 0.7× 10-6 copper sulfate according to the water depth per mu 1 m, which can kill moss. (2) For water with a depth of1meter, use 50 kilograms of gypsum powder per mu, and spray it all over the pool for three times, with an interval of 3-4 days. If the amount of moss is large, the dosage can be increased to 65 kilograms of gypsum powder per mu, and applied after the rain in the afternoon. If conditions permit, fresh water of 10 ~ 20 cm can be injected after smearing, and the effect will be better. Gypsum powder can prevent moss, which will neither dilute the pool water nor cause hypoxia in the pool water. Generally, all mosses can be killed within half a month, and the effect is better than that of copper sulfate.