A complete collection of pond cleaning methods for aquaculture

Quicklime

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Sources and main components of quicklime

All natural rocks with calcium carbonate as the main composition, such as limestone, chalk, dolomitic limestone, etc., can be used to produce lime. In the process of producing quicklime, the natural rock which is mainly composed of calcium carbonate is calcined at the temperature of 1000-1100 ℃. After removing the decomposed carbon dioxide, the product with calcium oxide (CaO) as the main component is quicklime.

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Principle and usage of quicklime pond cleaning

[principle of clearing ponds with quicklime]

After meeting water, quicklime produces calcium hydroxide and releases a lot of heat. Calcium hydroxide is a strong alkali, which can raise the pH of the pond water to more than 11 in a short time. In the process of cleaning the pond, if the pH value of the pool water exceeds 11 and can be maintained for more than 2 hours, it can achieve the purpose of killing enemy organisms and pathogenic microorganisms, and can effectively kill wild miscellaneous fish, frog eggs, tadpoles, aquatic insects and so on.

[method of clearing ponds with quicklime]

Method 1: dry cleaning of the pond

First drain the pond water, or leave water 5-10 cm, with 50-75 kg of quicklime per mu, depending on the amount of silt at the bottom of the pond. When cleaning the pond, dig a few small pits at the bottom of the pond, then put the quicklime into the melt, and sprinkle the whole pool evenly without waiting for cooling.

The next morning can be turned over with a rake, the purpose is to let it and silt mixed, give full play to the role of quicklime pond cleaning disinfection.

Method 2: clean the pond with water

Quicklime is used at a depth of 1 meter per mu with 125 MUR 150 kilograms. Quicklime is usually put into the boat and sprinkled throughout the pool immediately after the quicklime is melted.

Fish fry can be released 7-9 days after clearing the pond. In this method, there is no need to add new water before seedling, which prevents wild miscellaneous fish and diseases and insect pests from entering the pond with the water, so the disease prevention effect is better than the dry pond cleaning method, but the dosage of quicklime is larger, the labor cost is high and the cost is high.

[other functions of quicklime in pond cleaning]

In the process of cleaning the pond with quicklime, some other functions are easy to be ignored. Quicklime can not only clear the pond, but also supplement the calcium ions in the water body and improve the hardness of the water body, which is especially important in the process of shrimp and crab culture. In addition, as the main raw material of quicklime is natural rock, it can effectively supplement trace elements in water, which are necessary for the growth of aquatic animals and plants.

[matters needing attention in the use of quicklime]

In the saline-alkali ponds in the north of ①, the use of quicklime to clean the ponds will increase the alkalinity of the bottom of the ponds, resulting in the problem of too high pH after seedling release. In this case, it is recommended to use bleach instead.

② is hydrolyzed because quicklime is easy to absorb carbon dioxide and water in the air. In the process of the selection and purchase of quicklime, it is best to choose block lime, which needs to be arranged according to the needs of production. It can not be stored too much and for too long at a time, so as to avoid the formation of calcium carbonate and failure.

Second, tea meal

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Sources and main components of tea meal

Tea meal, also known as tea seed cake, alias tea bran, tea withered, tea seed cake. It is a purple-brown granule, which is the cake made from the residue of Camellia oleifera oil after the oil is pressed. It is a commonly used fish input for aquaculture in China to clear ponds and kill wild miscellaneous fish.

The principle of killing fish is that the tea meal contains 12-18% diosgenin, also known as saponin, which is a hemolytic toxin that binds to heme in the blood cells of aquatic animals, resulting in the decomposition of blood cells and the death of aquatic animals. The tolerance of shrimp and crab is more than 40 times that of fish. the main reason for the different tolerance of fish, shrimp and crab to tea bran is that their hemoglobin is different, the hemoglobin of fish contains ferrous heme, and the hemoglobin of shrimp and crab is hemocyanin containing copper. Saponins mainly interact with heme and can kill wild fish, frog eggs, tadpoles, snails, leeches and some aquatic insects. It also showed certain toxicity to shellfish and sand silkworm in water, but had no killing effect on pathogenic bacteria and aquatic plants.

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Usage and dosage of Qingtang

It is recommended to clean the pond with water and the water depth is 30cm-50cm, so as to move the boat containing the soaking liquid of tea meal, so as to facilitate the uniform sprinkling of the whole pond. The dosage is 20-30 kg per mu when the water depth is 30-50 cm, and the dosage is adjusted according to the number of aquatic animals drilling mud of Loach and rice field eel in the pond. When using tea meal to clear the pond, it is necessary to crush the tea meal and soak it for 24 hours in order to facilitate the release of the effective ingredient (diosgenin) in the tea meal, which generally lasts for 7-10 days. The seedlings can not be released until the efficacy disappears.

For example, when there are many aquatic animals in the mud drilled by Loach and Monopterus Albus, the whole pond will be soaked with 0.15 meters of water one or two days before cleaning the pond, and tea meal will be used to clean the pond after the Loach and Monopterus Albus are drilled out of the sediment, the killing effect is more thorough.

As tea saponin is easily soluble in alkaline water, 1.5 kg quicklime is added to every 50 kg of tea meal when used, the efficacy is better.

In addition, tea meal is rich in nutrients such as crude protein and a variety of amino acids. After clearing the pond, it is conducive to the mass reproduction of plankton, and it is a good organic fertilizer for basic bait organisms. It can play a role of fertilizer and water in ponds with little silt and poor sediment.

Third, bleaching powder

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The principle of clearing the pond

Bleaching powder is a mixture of calcium hydroxide, calcium chloride and calcium hypochlorite. Its main component is calcium hypochlorite [Ca (ClO) 2], which is prepared by full contact between hydrated lime and chlorine. The exothermic chemical reaction occurs as follows:

Bleach powder appearance white or gray-white powder or particles, has a significant chlorine odor, very unstable, strong hygroscopicity, easy to be decomposed by light, heat, water and ethanol. Bleach dissolves in water. Bleaching powder generally contains about 30% available chlorine, and it will produce extremely unstable hypochlorite when it comes into contact with water. The chlorine and oxygen atoms produced by the decomposition of hypochlorite will have a strong bactericidal effect through oxidation and chlorination. Therefore, it has a strong killing effect on pathogenic microorganisms in aquaculture water, and can kill aquatic insects, tadpoles, snails, wild fish and some clams.

As bleach is easy to absorb moisture and dissolve, it needs to be purchased according to the needs of aquaculture production in the process of use, and it is not appropriate to purchase too much at one time, so as to avoid the decrease of available chlorine content caused by long storage time and decomposition failure.

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Usage and dosage

After dissolving the bleach with water, immediately sprinkle it all over the pool. It is recommended to drain the water to 30-50 cm and then clean the pond to facilitate the movement of the boat with bleach solution and sprinkle the whole pool after the bleach is fully dissolved.

After 3-5 days, the fish fry can be released if the medicine disappears completely. It is best to test the water before releasing seedlings to make sure the medicine disappears.

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Points for attention when using

The main results are as follows: (1) the effect of pond cleaning is closely related to the environment. Clear pond is suitable for sunny days, so the temperature of the water body is higher, the effect of drugs is relatively strong, and can improve the effect of clearing pond. If clearing the pond, long-term low temperature, pond cleaning drugs are difficult to degrade, easy to precipitate at the bottom of the pond, adsorbed by sand, slow release can easily lead to the death of released seedlings.

(2) the bleach should be packed in a wooden or plastic container, the whole pool should be sprinkled after the water is fully dissolved, and the residue should not be poured into the pond. Bleach should not be filled in a metal container, otherwise it will corrode the container and reduce the efficacy.

(3) Safety measures should be taken when applying bleach, and operators should wear masks and rubber gloves. At the same time, drugmakers should apply medicine in the upper wind to prevent the drug from blowing in the face and causing poisoning and clothing contamination and corrosion.

(4) if the active ingredient of bleach used is less than 30%, the application amount of bleach should be increased appropriately, and if the bleach has deteriorated and failed, it should be prohibited.

4. Pyrethroids

Aquatic products are mainly used to kill aquatic insects that have not been completely killed in the previous process of clearing the pond or in the process of adding water before the seedling. It has contact killing and stomach toxicity, accumulating acetylcholine on the synapses of the nervous system, abnormal permeability of nerve cell membrane, inhibition of nerve conduction, excitement and paralysis of insects and larvae.

When used in the national standard pyrethroid pond cleaning, the dosage is 5-10 times that of the normal treatment of parasitic diseases, which can effectively kill wild miscellaneous fish, shrimp and crabs, crustaceans, aquatic insects and so on.

Crustaceans such as crayfish, river crab and green shrimp are sensitive to pyrethroids, and pyrethroids dissipate for a long time, so it is easy to cause drug residues. In East China, many farmers have the habit of using pyrethroids bubble ponds. In the process of river crab culture, many farmers report that the incidence of "water turtle seeds" in river crab culture ponds with pyrethroids cleaning ponds is higher than that without pyrethroids cleaning ponds. Therefore, pyrethroids are not recommended in shrimp and crab culture ponds. After the fish fry pond is cleared with pyrethroids, the relevant detoxification products must be used before the fry is released. It is necessary to test the water of the fry and confirm that there is no problem before releasing the fry.

5. Comparison of various pond cleaning drugs

In the process of cleaning the pond with quicklime, bleach and tea meal, quicklime can kill wild miscellaneous fish and enemy organisms in a wide range, and it is easy to form a peak of plankton after cleaning the pond. it can provide biological bait for fish fry in the lower pond in time, which is the first choice of pond cleaning medicine.

Although tea meal pond cleaning contributes to the formation of plankton peak in pond water, it has a narrow killing range for enemy organisms and has no killing effect on pathogenic microorganisms, shrimp and crabs.

The killing range of bleach to enemy organisms and wild mixed fish is close to that of quicklime, but because it has a certain algae killing effect, it is not conducive to the formation of plankton peak after cleaning the pond.

Pyrethroid cleaning pond is mainly used to kill aquatic insects and other enemy organisms in the seedling pond, which has a large residue, and the drug itself is also contrary to the increasingly advocated concept of environmental protection and healthy breeding. Therefore, in the process that it is not suitable to use pyrethroid clear pond shrimp and crab culture pond, it is suggested to use quicklime to clean the pond, kill the enemy organisms in the pond water, and do not add water before seedling, so as to avoid the entry of aquatic insects and other enemy organisms.

Transferred from the official website of Daya Agriculture