How to remove duckweed in shrimp and crab ponds?

It is spring now, and the weather is getting hotter and hotter. Liu, the instructor of Liuyuan Village, Xin 'an Town, guannan county, went to his demonstrator Liu Gangxian's house to engage in loach breeding, with a breeding area of more than 500 mu. When he came to the loach pond, there were several rectangular green plants on the water in Liu Faxian, and he didn't know it was cress until he asked. Before loach breeding, the water quality is easy to deteriorate, and the newly adjusted water deteriorates for a short time. The root system of Oenanthe javanica absorbs rich nutrients in water, which can replace chemical drugs to regulate water quality, effectively reduce ammonia nitrogen and nitrite in water, adsorb suspended solids in water and purify water quality. However, it should be noted that chemical fertilizer should not be used in loach interplanting, otherwise it will affect the growth of loach. The farm not only grows water celery on the water surface, but also plants grapes around the pond mouth, which on the one hand plays the role of circulating culture, on the other hand, it also plays the role of providing a hidden place for loach. Another method is to use aquatic em bacteria: 1, which can effectively improve water quality, promote the decomposition of floating organic matter such as residual bait, degrade harmful and toxic substances such as ammonia nitrogen, nitrite and hydrogen sulfide, increase dissolved oxygen in water, promote the growth of beneficial plankton in water, and adjust the microbial ecological structure of aquaculture ponds; 2. Enhance the immune function of aquatic animals, prevent diseases, improve health and reduce morbidity and mortality; 3. Quickly purify the sludge at the bottom of the pond, balance the PH value, reduce the stress phenomenon of aquatic animals and create a healthy aquaculture water environment; 4. Quickly stabilize water color and cultivate beneficial bacteria and algae. Especially for black water, turbid water and red water caused by excess organic matter, the improvement effect is obvious; Usage: 1 Pond treatment: one week before the pond is filled with water, use 100 ~ 300 times of nongshengle instead of lime and bleaching powder to disinfect and purify the pond, and use 0.5 ~ 1 kg per square meter. 2. Water purification: 3 ~ 10 days before stocking, spray the water surface with Nongshengle at a depth of one meter, and use 1 ~ 2kg for an acre of pond. Depending on the water quality, 15 days 1 time, 1 month 1 time, where the water quality is poor. 3. Feed treatment: 0.2% Nong Le Sheng is added to every 100 kg feed, which is fed after being mixed evenly.