The main components of bleaching powder are calcium hypochlorite (containing 32%-36%), calcium chloride (29%), calcium oxide (10%-18%), calcium hydroxide (15%) and water (10%). It is a white granular powder, smelly, soluble in water, the solution is turbidity, poor stability, and gradually absorbs water and carbon dioxide in the air. In the general process, the available chlorine will gradually decompose. Bleach powder is a widely used disinfectant and water quality improver in aquaculture. After the bleaching powder is dissolved in water, hypochlorous acid and hypochlorous acid are produced, and hypochlorous acid can release active chlorine and initial ecological oxygen. It can kill bacteria, viruses, fungal spores and bacterial spores to different degrees. In addition, because the bleaching powder contains about 15% calcium hydroxide, the ph value of the pool water can be properly adjusted, and the formation of flocculation precipitation of calcium hydroxide in the water can adsorb organic matter and gum, so that the pool water is improved. The role of bleaching powder in aquaculture:

1. Pond cleaning and disinfection

Dry pond cleaning, the amount of bleaching powder is 10-30 g/m2; With water to clean the pond with 20 grams/cubic meters of water all over the pond. Can kill bacteria, parasites and other pathogens, but also can eliminate wild fish and other enemy organisms. After cleaning the pond 4-5 days after the drug disappears, you can inject new water, free aquatic animals.

2. aquaculture water disinfection

In the epidemic season (April to October), different disinfection methods are planned for different breeding objects. Generally divided into the whole pool sprinkling method and hanging bag method. For the prevention and control of bacterial diseases of carp fish, the concentration of water drugs is 1-2 mg/l. Around the food farm, the method of hanging bags is usually used for the prevention and treatment of bacterial diseases, and the number of hanging bags depends on the size of the pond and the number of farms. Usually hang 3-6 bags around the food field, each bag containing 100-150 grams of bleach powder.

Prevention of bacterial diseases of freshwater farmed fish: Periodically sprinkle bleach powder 2-3 times a month during the epidemic season at a dose of 1 mg/l (containing 30% of available chlorine).

Treatment of bacterial diseases and syndromes of freshwater cultured fish: Sprinkle bleaching powder all over the pool, so that the concentration of medicine in the pool water is 1 mg/l.

Bacterial diseases such as skin rot, furunculosis and red bottom plate of turtle: Use a bleach powder aqueous solution bath with a concentration of 1.5 mg/l. Use once a day for 2-3 days.

3. body disinfection

For fish and crab, use an aqueous solution of 10-20 mg/L of bleach powder (30% of available chlorine) for 10-30 minutes. Kill bacteria on body surface and gills; The surface of turtle can be disinfected with a concentration of 10 mg/l of bleach powder aqueous solution for 1-5 hours.

4. Disinfection of breeding sites and tools

Wooden or plastic tools should be soaked and disinfected with 5% bleach powder solution, and then washed with water before use; Aisles of breeding sites and food processing workshops can also be sprayed with 5% bleach powder aqueous solution for disinfection.

5. Sterilize the bait

The water grass should be clean and fresh. In the epidemic season, water plants can be disinfected, soaked in an aqueous solution of bleach powder with a concentration of 6 mg/L for 20-30 minutes, and then washed with clean water before feeding. Can prevent the occurrence of intestinal diseases. Precautions for use:

The effective chlorine content of bleach powder sold on the market is generally 25%-32%, and if the content is less than 15%, it can not be used. Use the correct calculation of the amount of medicine, use now. It has corrosion and bleaching effects on items, avoid using metal utensils. Store in a cool and dry place, away from sunlight, heat and humidity. Avoid mixing with acid, ammonium salt, sulfur and many organic compounds when used.