In daily life, plastic buckets can be seen everywhere, but they can't be used arbitrarily. Do you know that many times we need to pay attention to them? What should we pay attention to? The plastic buckets shall be arranged in a well lit and well ventilated culture room. In high temperature season, the buckets shall be arranged under a special shed with four sides ventilation to avoid the influence of too high temperature on the growth of unicellular algae. Before the seed expansion operation, the hands shall be washed and wiped with alcohol cotton for disinfection. The ladles with algal solution and culture solution, the measuring cylinders or cups with nutrient salt, the gauze and nylon film covering the mouth of the barrel, and the inflation tube shall be used after boiling and disinfection. The culture medium for seed expansion is prepared by boiling, cooling and adding nutrients. During the day, the air is continuously inflated, and at night, it is not inflated at noon in high temperature season. The plastic bucket shall be numbered and marked with the date of expansion, so as to facilitate the inoculation of three-level culture pool according to the sequence of expansion. Bottle to barrel, barrel to barrel and barrel to pond are continuous inoculation processes. Algae species must be pure and in exponential growth period, and polluted and aged algae species cannot be used for inoculation.