Detailed Explanation of Common Pond-Clearing Drug Types and Their Methods of Use

Drug-based pond clearing is the use of drugs to kill pathogens, parasites, and various predatory fish, wild trash fish, and other harmful organisms in the pond that endanger fish, shrimp, and crab fry, thereby preventing disease from affecting the normal growth and development of the cultured species and improving aquaculture efficiency. At present, there are many varieties of pond-clearing drugs, but different varieties have different effects. Commonly used pond-clearing drugs include quicklime, bleaching powder, tea seed cake, ammonia water, croton, Tangkening, and others.

1. Quicklime pond clearing Quicklime is calcium oxide. Its pond-clearing effect is that after quicklime meets water, a chemical reaction occurs, producing calcium hydroxide and releasing a large amount of heat. Calcium hydroxide is a strong alkali, and its hydroxide ions can raise the pH value of the pond water to above 11 in a short time. Thus it can quickly kill wild trash fish, various eggs, aquatic insects, snails, moss, parasites and pathogens and their spores, etc. At the same time, quicklime reacts with water and becomes calcium carbonate. Calcium carbonate can make the silt become a loose structure, improve the aeration conditions of the bottom mud, accelerate the decomposition of organic matter in the bottom mud, and, together with the replacement effect of calcium, release nutrients such as nitrogen, phosphorus, and potassium adsorbed by the silt, making the pond water more fertile and playing an indirect fertilizing role. There are two methods for quicklime pond clearing: dry method pond clearing and water-carrying pond clearing.

Dry method pond clearing: First drain the pond water or keep a water depth of 5-10 cm, dig several small pits in the pond bottom, use 70-75 kg of quicklime per mu, and increase or decrease by about 10% depending on the amount of sludge at the pond bottom. Put the quicklime into the small pits or emulsify it in a water vat, etc., and immediately and evenly sprinkle it over the whole pond before it cools. On the next morning, it is best to use a long-handled mud rake to rake the pond mud, fully giving play to the disinfecting effect of the lime and improving the pond-clearing effect. Generally, after 7-8 days when the drug effect disappears, fish can be released.

Water-carrying pond clearing: For ponds that cannot be drained before pond clearing, water-carrying pond clearing can be carried out. For each mu with a water depth of 1 m, use 125-150 kg of quicklime. Usually, put the quicklime into a wooden bucket or water vat to dissolve, then immediately, while hot, evenly sprinkle it over the whole pond. After 7-10 days, when the drug effect disappears, fish can be released. Practice has proved that water-carrying pond clearing has a better disease-prevention effect than dry method pond clearing. Water-carrying pond clearing does not require adding new water, avoiding the introduction of pathogens and harmful organisms with the water when water is added after pond clearing. The disadvantage is that the cost is high and the amount of quicklime used is relatively large.

Whether water-carrying pond clearing or dry method pond clearing is used, after such quicklime pond clearing, the pond-clearing effect can be achieved within several hours, and the disease-prevention effect is good. However, it must be noted that water bodies with relatively strong alkalinity cannot be cleared by this method.

2. Bleaching powder pond clearing Bleaching powder generally contains about 30% effective chlorine. Through hydrolysis it produces hypochlorous acid, and hypochlorous acid immediately releases nascent oxygen, which has a strong sterilizing effect and kills harmful organisms. When applying, first dissolve the drug with water in a wooden bucket, then immediately and evenly sprinkle it over the whole pond. After sprinkling, use a boat and bamboo poles to stir in the pond so that the drug is evenly distributed in the water body, thereby increasing the drug effect. For each mu of pond with a water depth of 1 m, use 13.5 kg. After 4-5 days, when the drug effect disappears, fish can be released. Bleaching powder has a very strong sterilizing effect, but it is easily volatile and deliquescent. Before use, its effective content should first be tested. If the content is insufficient, the dosage needs to be appropriately increased.

3. Ammonia water pond clearing Ammonia water is a very good liquid nitrogen fertilizer and is strongly alkaline. High-concentration ammonia water can cause a significant change in the pH value of the pond water, can kill wild trash fish, and has a sterilizing and insect-killing effect, with a relatively good disease-prevention effect. When using, generally drain the pond water or keep a water depth of 6-9 cm, use 12-13 kg of ammonia water per mu, add an appropriate amount of water, and evenly sprinkle it over the whole pond. After 4-5 days, water can be added and fish released.

4. Tea seed cake pond clearing Tea seed cake, also called tea seed cake, is purple-brown granular and is the residue left after oil extraction from the fruit of plants in the Theaceae family. Tea seed cake contains saponin, also called saponin glycoside, and can kill various wild trash fish such as @#@237@#@, river snails, freshwater mussels, frog eggs, tadpoles, and some aquatic insects. Tea seed cake has a relatively high protein content and is a highly effective fertilizer. It can play a fertilizing role for ponds with little silt and poor bottom substrate. For pond clearing with tea seed cake, water-carrying pond clearing is generally used. When using, first crush the tea seed cake, soak it in a vat, take it out the next day, and sprinkle it into the pond together with the residue and water. The dosage is 40-45 kg per mu for a water depth of 1 m. Because saponin is easily soluble in alkaline water, when using, add 1.5 kg of salt and 1.5 kg of quicklime per 50 kg of tea seed cake for a better drug effect.

5. Croton pond clearing Croton can only kill most wild trash fish, and the toxicity disappearance time is longer than the previous several types. Therefore, after using croton for pond clearing and disinfection, it takes about 10 days before @#@233@#@ fry can be released, and when the fry are put into the pond, it is necessary to test the water to check the toxicity of the pond water. When using, first crush the croton with water, then soak it for 3 days, and when putting it into the pond, sprinkle the residue and juice over the whole pond. The dosage is an average water depth of 1 m and 3-5 kg per mu.

6. Tangkening Tangkening is a new type of plant extract concentrated through a special process, and is a green and environmentally friendly pond-clearing agent. This product specifically kills fish, loach, tadpoles, river snails, Oncomelania snails, etc. It can be used for pond clearing during shrimp and crab culture, and even at five times the dosage it is still safe for shrimp and crabs. For clearing shrimp and crab ponds, it has an effect that other drugs cannot replace. When using, put this product into a bucket, add 50-100 kg of water, stir thoroughly, and then evenly sprinkle it over the whole pond. The dosage is that 1 kg of this product can be used for 6 mu at a water depth of 15 cm, that is, 1 kg per mu for a water depth of 1 m. Because this product is easily soluble in alkaline water, when using, add 3 kg of salt and 3 kg of quicklime per 1 kg, mix, add water, stir evenly, and sprinkle for a better effect. When this product is used alone to kill snails, the dosage can be reduced to save costs.