Polyaluminum chloride manufacturers share the secret of "raising water first" aquaculture

It is well known that "farming water first", and the water body is the environment in which fish and shrimp grow, live and live. however, the interaction between pond sediment and water may strongly affect the water quality, so if we want to raise water well, we must start with the improvement of pond bottom quality. full attention must be paid to the management of pond sediment. "Xintangwang three years" is a true portrayal of pond culture. In order to achieve sustainable development of pond culture and reasonable maintenance of pond soil and water resources, it is necessary to improve and repair the deteriorated pond sediment. How to repair the deteriorated substrate? The editor of 100 million liters of polyaluminum chloride will share with you:

I. the main characteristics of the sediment of the pond

The bottom of the pond is not only used as a holding tank for aquaculture and the storage of various chemicals, but also the habitat of plants, animals and microorganisms and the core of nutrient recycling. Matter has been precipitated from the pond water to the bottom of the pond, such as suspended solids in surface runoff into the pond, fertilizer and unfed residual bait, and carcasses of animals and animals in the water. Substances may also enter the solid phase of the soil at the bottom of the pond through ion exchange, adsorption and precipitation, and the substances that enter the sediment may be stored forever. or it can be transformed into other substances by physical, chemical or biological methods and lost from the pond ecosystem. The organic matter deposited at the bottom of the pond is usually decomposed into inorganic carbon and released into water in the form of carbon dioxide. Nitrogen-containing compounds are denitrified by microorganisms in the pond sediment and lost to the atmosphere in the form of nitrogen. Phosphorus is absorbed by the pond sediment and buried in the sediment to enter the cycle of available phosphorus pool, and sulfur-containing compounds produce hydrogen sulfide by reducing bacteria. And then combined with the metal ions (iron, manganese, etc.) in the pond sediment to form black sulfides and settle on the sediment.

The bottom soil of the pond is the living place of some bacteria, fungi, advanced aquatic plants, small invertebrates and other benthos. In addition, crustaceans and benthic fish also live at the bottom most of the time. Many fish also nest and lay eggs at the bottom. Microbial decomposition occupies a very important position in the bottom nutrient cycle, because through pyrolysis, organic matter is oxidized to carbon dioxide and ammonia, and other mineral nutrients are released, so that through microorganisms, carbon, nitrogen and other elements can still be used by mineralization or recycling. However, if the equilibrium concentration of a certain nutrient is too low, it may not be conducive to the growth of phytoplankton, or if the equilibrium concentration of a heavy metal element is too high, it can cause poisoning of aquatic animals.

The particle size and texture, pH value and acidity, the characteristics of organic matter, nitrogen concentration and carbon-nitrogen ratio, the depth of sediment and the concentration of nutrients can affect the treatment of culture ponds. The active components of bottom soil should be clay particles with large nominal product of electric charge and organic materials with biological applicability and high chemical activity. The characteristics of pond sediment are closely related to the yield of aquaculture, and the growth and development and water quality indexes of different sediment water are also different.

Second, the damage caused by the deterioration of pond sediment.

After a period of culture in the pond, a part of organic particles such as residual bait, manure, fertilizer, dead algae and so on sink into the bottom of the pond, and the dead organisms after fermentation and decomposition are mixed with sediment at the bottom to form sediment. A certain thickness of sediment can play the role of fertilizer supply, fertilizer conservation and regulating and buffering the gradual change of pond water quality.

The organic decaying substances in the sediment and the harmful substances such as carbon dioxide, ammonia nitrogen, nitrite, hydrogen sulfide and a variety of organic acids produced by decomposition of dissolved oxygen are good cultivation bases for pathogens or hidden dwellings of various parasite eggs. The deterioration of thick sediment can cause serious harm to fish, and this harm is indirect in most cases. In the feeding pond, the residual bait and the excretion of fish and shrimp cause a large number of phytoplankton in the pond, which control the change of dissolved oxygen in the pond. During the day, the oxygen produced by photosynthesis is greater than the oxygen consumption of respiration, and the concentration of dissolved oxygen is higher, but it is just the opposite at night. With the input of a large amount of bait, in our breeding process, especially in the later stage of culture, the phenomenon of algal bloom is very widespread. In addition, if the concentration of organic matter in the bottom of the pond is too high, it will be conducive to the formation of anaerobic conditions at the bottom of the pond, resulting in the production of toxic metabolites of microorganisms, the increase of harmful substances such as ammonia nitrogen and nitrite, and further aggravate the blackening and smelly of the bottom of the pond. the water quality deteriorated and parasites and bacteria multiplied in large numbers. Therefore, sediment, water quality and diseases are closely related.

III. The main factors for the deterioration of sediment

1. The cleaning of the pond is not complete, the time of drying the pond is too short, the drugs used in cleaning the pond are improper, and there are too many drug residues caused by the cleaning of the pond.

2. During the period of culture, too much organic matter remains and the bottom is lack of oxygen, which is the most important factor for the deterioration of sediment. The residues of organic matter such as residual bait, feces and biological corpses lead to a sharp increase in biological and chemical oxygen consumption, and the dissolved oxygen at the bottom of the water body is helpless to satisfy the oxygen consumption, resulting in anoxia in the bottom of the pond and the breeding of a large number of anaerobic bacteria. a large number of toxic side products are produced by decomposing the organic matter at the bottom, such as ammonia nitrogen, nitrite, hydrogen sulfide, methane, organic acid and other harmful substances. These poisons not only have great toxic effects on aquatic animals, but also cause a large number of pathogenic bacteria, hypoxia floating head and so on.

3. A large number of frequent use of chemical disinfectants, pesticides, algaecides, etc., thus damaging the self-purification capacity of water and sediment.

4. Poor substrate

1. Sour and fishy substrate

The cause of formation: there is too much decaying organic matter at the bottom of the pond, mainly due to incomplete pond cleaning, redundant bait in the breeding process, failure to take measures to improve the bottom material on time, etc., in addition, insufficient oxygen-increasing measures and irregular throwing of oxygen-increasing agents, so that organic matter has not been fully oxidized and decomposed, [E.N.] symbiotic sharing meeting with stars and winter night sky observation movement stopped happily! A large number of toxic intermediates are produced, such as ammonia nitrogen nitrite, hydrogen sulfide, methane and so on. When the substrate is severe, a large number of harmful gases will be produced, resulting in a "bubbling" scene.

2. Hardened substrate

Cause of formation: repeated use of chemical fertilizer, fertilizer and water, appropriate application of copper sulfate insecticide and algicide, large number of quicklime and other drugs, resulting in substrate hardening, the exchange of gas and nutrient elements between sediment and water is blocked, the buffer of water environment can be weakened, water quality is changeable, and aquatic animals are prone to stress reaction.

3. The bottom material of "mud skin"

Cause of formation: a large number of aging dead algae and suspended colloid deposits are deposited at the bottom, which will become floating skin and form a lot of foam on the surface of the water body after the action of microorganisms.

4. The substrate of "filamentous algae"

The cause: the exchange of nutrient elements between the sediment and the water body is blocked, resulting in the imbalance or lack of nutrient elements in the water body, showing "algae" and "turning water" (the water quality becomes clear overnight), the water quality is too thin and clear to the bottom. filamentous algae and green mud moss multiply in large numbers at the bottom.

5. "turbid" substrate

The cause of formation: too much organic matter remains and does not get sufficient oxidation and decomposition, which is released and suspended in the water body in the form of colloid, resulting in "turbidity" of the water quality; or the aquaculture Midu is too large, and the aquatic animals are constantly in turmoil at the bottom, resulting in "turbidity" of the water quality; or the water quality is "turbid" due to heavy rain with a large amount of clay slurry. "turbid" water quality, Hong Kong has won awards over the past 30 years, and we all grew up listening to these Hong Kong pop songs! When suspended and settled to the bottom, the sediment must be "turbid"; in addition, the "turbid" water quality will mask the use of algae and light, weakening the self-purification ability of the water body, causing a large number of pathogenic microorganisms and causing diseases.

6. "steal death" bottom material

Cause of formation: due to hypoxia in the bottom era, harmful substances such as ammonia nitrogen, nitrite, hydrogen sulfide, methane and organic acids accumulated too much, resulting in the poisoning and death of aquatic animals at the bottom, and a large number of dead bodies were discovered at the bottom during sowing.

V. measures for improving the sediment of ponds

In the production, more attention is paid to the improvement of the water body, which is said to be "looking at the water to cultivate fish", but does not pay attention to whether the bottom water is low oxygen, whether the sediment is smelly and blackened. We often encounter fish "floating head" or "pan-pond", many of which are the result of the deterioration of sediment. If the bottom quality is good, even if there is abnormal weather such as "heavy rain", it will not cause the rapid decrease of dissolved oxygen or the agile increase of harmful substances. We know that low dissolved oxygen not only makes the survival of farmed animals difficult, but also affects the food intake and digestibility of farmed animals, but also leads to the increase of harmful reducing substances (ammonia nitrogen, sulfides, etc.) and the increase of pathogenic bacteria in the water. thus affecting the stability of the water body and the growth and disease resistance of farmed animals. Therefore, the repair and improvement of substrate is of great significance.

1. Physical mode

Dredging is normally carried out in winter or early spring and other idle seasons. In most cases, the pond water is drained first, and then the hydraulic pond digging unit is used to clear the silt just like digging a new pond. This method has low cost and strong adaptability, but it needs water and large wasteland or shoals to discharge mud and let it precipitate. The production practice shows that the sediment thickness of silver carp and bighead carp ponds is 20 cm and 40 cm, and 10cm~15cm is suitable for grass ponds, bream ponds and carp ponds. Therefore, in order to maintain good water quality, the sediment with dark 10cm~20cm should be swept away every 12 years. The bottom of the pool is then frozen in the sun ("winter dry") to promote the decomposition of organic matter and destroy pathogens and other pests. During this period, the pond can also be repaired and strengthened, infarcted flaws, gates repaired and weeds removed, etc.

In production, it is sometimes necessary to clear the silt without draining the pool water. at present, the dredging machinery used can be divided into two types: ship-type dredging machine and submersible dredging machine. The main working parts of the ship-type silt cleaner are installed on the ship, and only the suction head is underwater, which can clean up the silt at the bottom of the pond during the culture period, and the suction operation continues; all the working parts of the submersible silt cleaner dive into the bottom of the pool and walk on the surface of the silt. while suction operation is carried out. However, because the whole machine is under water, the request for waterproof and sealing of the energy machine is high, and the maintenance skills are difficult, so it is inconvenient for users to take care of themselves and repair.

In addition to dredging, often stirring the bottom of the pond, loosening the silt at the bottom of the pond, and mixing the water up and down, it can also promote the decomposition of organic matter at the bottom of the pond and release the nutrients deposited in the sediment newly, restore the balanced distribution of nutrients in the high and low water layers of the pond, promote the growth and reproduction of plankton, thus avoiding the aging of the pond bottom; aeration by turning on the aerator can also improve the bottom environment and slow down the blackening process.

2. Chemical methods

The most commonly used chemical method is quicklime to clear the pond. After meeting with water, quicklime produces chemical reaction, releases a large amount of heat energy, neutralizes various organic acids in the sludge, and changes the acidic environment, which can play the role of disinfestation, fertilization, improvement of sediment and water quality. When in use, you can clean the pond with dry pond or clean the pond with water. Clean ponds with water generally apply lime timely and reasonably in ponds with low total alkalinity, total hardness and pH value, while quicklime is not needed if the concentration of calcium ion in pond water and sediment is higher and alkalinity is higher; quicklime should not be applied only in culture ponds with poor organic matter, otherwise it will aggravate the decomposition of organic matter, make the backlog of organic matter less, pond fertility further drop, and recovery is more difficult.

In addition to quicklime, chemical compound substrate improver can also be selected. For example, a white granular "bottom water quality improver", which is mainly composed of calcium peroxide, can rapidly increase oxygen, promote nitrification, reduce the content of ammonia nitrogen, nitrite and sulfide in water, and make up for the calcium needed for biological growth. and make the bottom matter fluffy and breathable, using the complete decomposition of organic matter. At present, a new type of nitrite ion remover? Nitrite chelating agent (BRT) and its salts can degrade nitrite nitrogen and ammonia nitrogen in pond water, chelate organic matter in pond water, and remove the pollution of heavy metal ions in pond water and bottom, etc., so they can be used as pond soil improver, sediment improver and sediment activator. Represented by flocculants such as polyaluminum chloride, aluminum sulfate and alum, the water will be delaminated after use, the middle and upper water will become clear, and there will be a large number of cloud-like flocculants at the bottom.

3. Biological methods

The obvious effect can also be obtained by using biology to repair the bottom of the culture pond and reduce the accumulation of organic matter in the bottom. It is reported that transplanting Bombyx mori and other benthos in aging and polluted shrimp ponds and cultivating them into an upwind population can ingest a large amount of residual bait, feces and other biological bodies and organic debris in the shrimp ponds, slowing down the accumulation of organic matter at the bottom of the shrimp ponds. And the silkworm camp lives in caves, and the continuous movement of its bristles can become a small flow cycle, which can increase the dissolved oxygen in the sediment.

Microbial preparations such as photosynthetic bacteria and compound probiotics can also improve the sediment of the pond. Photosynthetic bacteria can reproduce in the rich bottom of the pond, such as light, organic matter, hydrogen sulfide and so on, and use these substances to build themselves, while they are preyed on by other animals, forming the main link of material cycle and food chain in the culture pond. Therefore, photosynthetic bacteria can play a more prominent role in closed culture ponds, especially in closed ponds with serious pollution at the bottom or poor water quality. The compound microbial substrate improver can exert the synergistic effect of various bacteria and eliminate the hidden dangers affecting the deterioration of the bottom capacity, such as residual bait, excreta, animal and plant corpses, etc., not only improve the sediment and water quality, but also control the spread of pathogenic microorganisms and their diseases.

4. Other:

The silt deposition rate is directly related to the feeding and management methods such as fertilization and feeding. Try to apply fertilizer according to water in production and avoid excessive; according to the principle of ecological complementarity, reasonable mixed culture and close breeding; feeding amount is controlled according to season, meteorology, growth condition and water environment; food attractants and growth promoters are added to feed to strengthen the appetite of aquatic animals, improve the reception and transformation of feed nutrients, reduce the feed coefficient, and solve the infection of excreta to sediment and water quality from the source. Control the growth of a large number of aquatic plants (especially filamentous algae) and remove excessive or dead aquatic plants in time to prevent erosion and deterioration; if there is a premise, you can throw ironmaking slag (ordinary 1.5kg/m3) into the blackening area to delay the blackening process and reduce persecution.

In addition, if the dry pond period is longer, you can consider the continuous cultivation of aquaculture and crops. This can make the silt more fully dry, rely on the developed roots of terrestrial crops, make the soil fully contact with the air, be conducive to the mineralization and decomposition of organic matter, better improve the bottom of the pond, and at the same time, obtain the economic value of the crops themselves. In addition, the growing green crops and forages can also be used as fine green manure for ponds and feed for fish.

The buffer capacity, self-purification capacity, production function and anti-adversity performance of pond bottom are the key to the success or failure of pond culture. "success is also the bottom quality, failure is also the bottom quality" for the pond farming industry is not too much. In order to enable the pond aquaculture industry to develop continuously and overcome the obstacles of continuous cropping, the regular improvement of pond sediment needs to be paid enough attention by pond farmers.

VI. Common substrate improvers

1, adsorption type: such as zeolite powder, Maifan stone, activated carbon, etc., it is only a simple physical adsorption of ammonia nitrogen, nitrous acid, organic matter and other harmful substances in the water, the water will become fresh after use, but the characteristics of the harmful substances themselves have not changed, just diluted in them, and settled to the bottom of the pool to increase the bottom odor.

2, flocculation type: represented by polyaluminum chloride, aluminum sulfate, alum and other flocculants, the water will be layered after use, the middle and upper water body will become clear, and there will be a large number of cloud-like flocculating gel at the bottom, so it will also aggravate the bottom hypoxia after use in production.

3, ion exchange type: like containing EDTA or sodium thiosulfate (sea wave)-based products, for reducing cationic harmful substances in the water or bottom ammonia nitrogen heavy metals, or for detoxification of positive oxides such as bromine chlorine iodine compounds, potassium permanganate, etc., the consequences are more fantasy, but the effect on the water or bottom negatively charged acidic harmful substances (organic matter) is very poor.

4. Living bacteria degradation type: at present, there are many biological base changes in the market, the main components are Bacillus subtilis, nitrifying bacteria, denitrifying bacteria and local zeolite powder as living bacteria carriers, sometimes adding sodium humate, trace elements and so on.

One kind is mainly oxygen-consuming living bacteria such as Bacillus, nitrifying bacteria and denitrifying bacteria, which must be in a high oxygen environment before they can exert their functions, and this kind of biological bottom modification will consume a lot of oxygen in use. especially the bottom aging ponds and ponds without oxygen equipment should be used with caution. The other is mainly photosynthetic bacteria, lactic acid bacteria, yeast and other anaerobes. And because it does not consume oxygen, its side effects are not taken seriously. Take yeast as an example, the process of changing the bottom of yeast is the process of fermentation, although this kind of fermentation is anaerobic fermentation, but the process of fermentation is the process of energy generation and heat production. the hypoxia caused by bottom heat will become more significant and harmful due to the more organic matter such as bottom residual bait feces, so live bacteria are used in production. It should be used in high temperature and rainy season as appropriate. In addition, the excessive organic matter at the bottom of many old ponds will not only cause bottom odor, but also breed a large number of protozoa (such as ciliates, rotifers, Cladocera, copepods). If living bacteria are selected to change the bottom, these zooplankton will directly feed on live bacteria, thus speeding up the reproduction of zooplankton. In addition, algae compete with autotrophic microorganisms such as photosynthetic bacteria and nitrifying bacteria, so excessive algae is not conducive to the reproduction of these bacteria, thus affecting the effect of bottom change.

5. Chemical degradation type: it is mainly composed of various halogens, alkaline metal salts and other oxidants and some surfactants. The sediment improvers of this type are all chemical degradation type. Whether the water of the same type of product is good or bad individually shows that the release of water is fast or slow. The faster the hydrolysis, the greater the irritation, and the slower the hydrolysis, the less the irritation. In addition, this kind of products are not affected by weather, water temperature and other environmental factors. These products are widely used in production.

7. Pay attention to matters

1. Before using all kinds of substrate improver, the aerator should be turned on 12 hours in advance, or 1 kg / mu of oxygenator should be used, and the effect of substrate improver should be better after sprinkling it in the whole pond.

2. Use all kinds of substrate improvers strictly according to the imitation sheet, and if the effect is not obvious once, use it again every other day. Do not overdose at one time.

3. Never use alum or some products containing aluminum to improve water quality.