natural water contains various chemicals, which will affect the survival rate of cultured organisms. In cities, tap water is almost neutral, but it contains chlorine, so it must be dechlorinated before it can be used for seafood preservation. The simplest way to eliminate chlorine is drying, which puts the water on hold for 3 days before using it; In places lacking light, it should be stored for a week before it can be used. In addition, chemical dechlorination can be used. The commonly used dechlorination drug is sodium thiosulfate (commonly known as hypo), and its reaction equation is:
Na2S2O3+4cl2+5h2o = = = 2nahso4+8HCl
Under general conditions, this reaction rate is very fast. After sodium thiosulfate is dissolved in water, the reaction can be completed with a little stirring. The dosage of sodium thiosulfate depends on the content of free chlorine in water. Generally, the dosage is 1kg tap water and 1g sodium thiosulfate.
2. Hardness of water and its adjustment
Hardness and pH are the two most important water quality factors.
water containing dissolved calcium, magnesium and iron salts is called hard water. The content of metal ions in water is an important factor to determine the hardness of water. When the content of calcium salt in water reaches 65mg/L, it is called neutral water. When it is less than 65mg/L, it is called soft water; When it is greater than 65mg/L, it is called hard water. The easiest way to judge hard water and soft water is to boil the water. If there is water and alkali at the bottom of the kettle, it is hard water, otherwise it is soft water. The hardness of water should be adjusted according to the requirements of the object to be kept.
3. the PH of water and its adjustment
the ph value is the concentration of hydrogen ions. The negative logarithm of hydrogen ion concentration in water is called the pH value of water.
According to the concentration of hydrogen ions in water, the pH of water can be divided into 14 grades.
generally speaking, water with pH < 7 is called acidic water, water with pH = 7 is called neutral water and water with pH > 7 is called alkaline water. There are two methods to determine the PH value: First, use litmus test paper and a colorimetric plate, put the test paper in water for 1 second, and then get the excellent result to know the PH value. Secondly, it is measured by a special PH meter. The simplest PH meter is slightly larger than a pen. When you insert it into the water and press the switch, the LCD can display the PH value.
The toxicity of many poisons also increases with the decrease of PH value. When the water is too alkaline, the gill tissue of fish will be corroded, which will affect the normal life of fish in seafood pool.
In the process of storage, the water in seafood pool sometimes becomes turbid, which may be caused by excessive feed, which makes the residual food soaked in the water, which is beneficial to the reproduction of bacteria and pathogenic bacteria. This will make the water quality deteriorate, produce rancid smell, and turn white or grayish white. At this time, the water should be completely replaced, the pond should be cleaned and disinfected, and the stored seafood should be taken out and disinfected with .3×1-6 disinfectant, and then put into the newly prepared water tank. At the same time, feed should be reduced or stopped as appropriate. If it is found that the residual feed residue is accumulated at the bottom of the box, siphon the residue out in time and clean it up. If the water is still turbid after changing, the sand and gravel in seafood pool should be thoroughly disinfected.
Sometimes, due to the abundant supply of goods, there are too many organisms in seafood pool and storage ponds, which will also cause the water to become turbid, because the excrement discharged by organisms will accumulate, which will make the water sour; The swimming of living things makes the dead things float, making the water mixed and dirty.
Chemical agents are mainly used to adjust the PH of water, the most commonly used ones are sodium dihydrogen phosphate and sodium bicarbonate. Before use, these two drugs should be dissolved in pure water, and sodium dihydrogen phosphate is used to reduce the pH value, that is, to increase the acidity of water. Sodium bicarbonate is used to improve the PH value, that is, to increase the alkalinity of water. When in use, the prepared solution can be gradually dropped into the water as needed, and fully stirred, and it should be continuously tested with PH paper until the pH value of the water meets the requirements. The change of acidity and alkalinity of water should be controlled within .1; Because the drastic change of PH value is very unfavorable for preservation. Experienced breeding managers can generally judge whether the water quality has deteriorated from the swimming style, appetite and water color of seafood. Once the abnormality is found, the PH value must be determined immediately. If the water quality is really unsuitable for keeping seafood, the water should be changed immediately.
4. Dissolved oxygen
Fish, shrimp, shellfish, etc. breathe dissolved oxygen in the water through gills. If fish floating heads are found during the storage period, it means that oxygen is lacking in the water. If measures are not taken immediately to increase the dissolved oxygen content in the water, all the creatures in the storage pond will often die.
from the ecological point of view, the effects of oxygen on fish survival can be divided into three categories: the dissolved oxygen content in water is more than 5.×1-6
, which is the suitable value for fish survival; Between 3.× 1-6 and 4.9× 1-6, the fish can barely survive; .3× 1-6 ~ 2.9× 1-6, which is not suitable for fish survival.
the content of dissolved oxygen in water is affected by the amount of various organic substances in the aquarium, the pressure and other factors.
Improving the water quality, increasing the illumination time, equipping with oxygen-increasing devices, increasing the number of water changes, reducing the number of preserved mantissa, filtering the water in the aquarium and adopting the water circulation system can all increase the dissolved oxygen content in the water.
5. Poisons
In the process of storage, chronic poisoning of stored organisms often occurs, which is caused by toxic substances in water. Generally, most of them will not have obvious symptoms in a short period of time, and they will usually die in 2-3 days.
In order to prevent poisoning, we should pay attention to prevent poisons from entering the aquarium, and carefully check whether the container is contaminated by pesticides during the transportation of fish.
6. Changing water
When the water quality is in the following situations, it is necessary to change all the water in the aquarium: 1. The water is turbid, resulting in abnormal odor; 2 fish nose up; 3 the fish is sick. In addition, even if there is no deterioration of water quality, it should be checked frequently.
Seafood purchased from farms or marine fish markets will be transported to cities for storage, and the source of seawater will be difficult, especially in inland areas, and it is often necessary to replace seawater, which has become a big burden for operators.
in order to solve the practical problems of seafood preservation, the researchers of Guangzhou Haishen Aquarium Science and Technology Service Company of Nanhai Fisheries Research Institute have successfully developed a closed-loop seafood preservation system after years of research and aquaculture experiments, which has solved the technical problems of seafood preservation. After years of practical application, it has proved its feasibility. They also used new technology to successfully develop scientifically prepared artificial seawater and solid seawater to replace natural seawater, and achieved satisfactory results. The new breakthrough of seafood preservation technology has brought good news to seafood preservation and operators.
3. Closed-loop system
1. Principle and main technical parameters of closed-loop system
Closed-loop system simulates and explores the ecosystem of natural waters by using the environmental protection treatment technology popular in the world at present, and applies it to aquarium conservation. The whole system integrates physical filtration, chemical regulation and biological purification, so that each link can not only give full play to its own performance, but also adjust each other to achieve the effect of purifying water. The whole water system can run for a long time, avoiding the deterioration of water quality, reducing the trouble of constantly changing water, saving manpower and material resources, and embodying the benefits of using modern aquarium technology to preserve seafood and aquatic products.
The main technical parameters of the closed circulation storage system designed and constructed by Poseidon Aquarium Science and Technology Service Company are as follows:
Storage capacity: 15kg/m3 for a long time (more than one week); Short-term (within one week) 3kg/m3 circulation: more than three times per hour for water; Water use time: more than 6 months;
PH value: within the suitable range; Ammonia nitrogen: within the suitable range; Salinity: can be adjusted at 1-4; Water temperature: 1-25℃ < P > 2. Characteristics and technical parameters of Poseidon brand solid seawater
(1) Characteristics < P > Poseidon brand solid seawater is developed by scientific researchers with reference to the chemical composition of natural seawater, which has the chemical elements of natural seawater and is added to the water quality balance system. Compared with natural seawater, seawater prepared with this seawater element has the following advantages:
A can be adjusted to the required salinity according to users' wishes;
B is pure in quality without any pollution;
C is not affected by weather and seasons;
D with wide balance system, it has stronger self-cleaning ability;
the sea water prepared by e has the ability to make diseases, which is beneficial to enhance the physical strength of preserving seafood;
F convenient transportation and storage.
(2) Main technical parameters
A. Salinity: it can be adjusted at will; B. pH value: 7.6-8.2; C. ammonia nitrogen: within the allowable range; D. The equilibrium system can purify toxic heavy metals in water.
3. Operation
(1) Preparation before preparing seawater
Before preparing seawater, it is necessary to recognize the trademark and packaging of Poseidon brand solid seawater. First, clean the circulating system, add clean tap water, adjust the water level, and check whether all kinds of equipment are running normally (including water pump, aeration, lighting, gas making, etc.), and then run for 24 hours to test the circulating water.
(2) Preparation of artificial seawater
After the inspection proves that the closed circulation system is operating normally, the seawater element is slowly added into the storage pond, adjusted to the required salinity, and circulated for more than 24 hours, so that the water quality can be extremely pure and can be used for storing seafood.
(3) Preparation before storage
Before storage, it is necessary to check whether the circulating system is operating normally, and whether the water temperature, PH value and salinity meet the required standards.
before storage, there should be a systematic plan for the placement of stored varieties, so that the stored varieties can adapt to their required salinity and temperature, and the number of stored varieties can adapt to the water capacity.
after the live seafood and aquatic products arrive at the destination, they should be sorted out first, and those who are dead, seriously injured and sick should be eliminated; Then washing, the washing method is that seafood can be washed with fresh water or 1×1-6 potassium permanganate solution for about one minute, or disinfected with .2×1-6 carbendazim, and freshwater fish can be washed with seawater or 1×1-6 potassium permanganate solution for one minute, or furazolidone can be used instead of potassium permanganate; After being washed, it is put into the storage pool of the circulation system for storage.
(4) Conservation management
The closed circulation system relies on water circulation to make the purification function of the system work and achieve the purpose of purification. Therefore, once seafood is put into the storage system, all links of the system can't stop running (including aeration, water circulation, temperature control, etc.).
In order to obtain ideal preservation effect, the whole management work, from the preparation and adjustment of salinity and water temperature, to the disinfection of seafood and aquatic products before preservation and the inspection of circulation system before operation, is very important. To manage the closed circulation system well, we need to do three tasks, namely, diligent inspection, diligent cleaning and diligent observation.
A regular inspection: check whether the system equipment is running normally, whether the inflation is sufficient, and whether the water flow is smooth.
B clean up frequently: clean up the dead seafood in the storage pond in time to avoid the deterioration of water quality caused by the decay of dead seafood;
C frequent observation: always observe whether the stored seafood has abnormal reaction and whether the water quality is kept in good condition. In case of any situation, find out the reason in time and deal with it immediately.
in addition, it is necessary to keep the environment around the storage system clean, especially to avoid any sundries in the storage pool of the system, and to prevent foreign unclean seawater and other chemicals from entering the filter bed. The upper gauze should be cleaned regularly (usually once a week), and the filter bed should be thoroughly cleaned once every six months.
Attachment: Preservation methods of abalone and mussel
Abalone and mussel are low-temperature and high-salt varieties, and their adaptation temperature is 12-15℃ and salinity is 3-33. Its preservation method is simple: firstly, prepare a refrigerator (beverage display cabinet), several thin plates made of metal or plastic and a sponge with a thickness of 1.-1.5cm; Then soak the sponge in prepared seawater, put it in a metal or plastic tray, put the tray in a refrigerator, then wash the abalone and mussel with seawater and evenly discharge it on the sponge; Then adjust the temperature of the refrigerator to the temperature suitable for abalone and mussel. Never put abalone and mussel in the storage pond for storage, otherwise the loss will be serious.
iv. Aquarium oxygenation circulation system
With the continuous development of society, aquarium technology has attracted the attention of various countries in recent years, and many developed countries have paid more and more attention to the research and manufacture of aquarium and made some innovations. Now the aquarium has entered the family for people to enjoy. The design of the aquarium not only pays attention to beauty, but also requires science, and provides a living environment like the natural environment for the preserved creatures. This paper introduces a new type of aquarium oxygenation circulation system suitable for raising ornamental fish in families or shopping malls. The system has the functions of oxygenation, circulation and physical filtration. The box has no metal frame and is completely transparent, which is practical and convenient to watch.
the structure of seafood pool oxygen-increasing circulation system is: a fully transparent water tank with a length, a width and a height of 1cm×5cm×5cm, which is made of glass with a thickness of 1mm, and its capacity is about 2L l. There are many off-duty partitions near the bottom of the aquarium, which are used to carry coral sand and prevent it from leaking out. Coral sand with a thickness of 3-5cm is laid on the partition as a physical filter layer. Under the partition, filtered water enters the partition frame through the water pipe. The capacity of the partition frame is about 1/15 of the total, which is located at the edge of the aquarium; A suction pipe with an inner diameter of about 2.5cm is arranged in the partition frame, and air is inserted into the suction pipe near the bottom through a thin hose.
The specific working process of the oxygen-increasing circulation system is as follows: the air output by the air compressor is limited by the narrow pipe wall, and the air bubbles float up to force the water in the pipe to rise with it, and then it reaches the nozzle at the upper part of the suction pipe and then rushes into the aquarium from top to bottom. Because the water flowing into the aquarium is driven by bubbles, the dissolved oxygen content of this water is high. After the water in the partition frame is pumped, the water level drops, forming a water level difference with the water level in the aquarium. According to the principle of physical connector, the water in the aquarium seeps through the coral sand by its own gravity, and then enters the water storage area at the bottom of the box through the gap of the glass partition, and then flows into the partition frame through the gap between the water pipe and the partition glass. In this way, water can be used repeatedly.
The aquarium with this oxygen-increasing circulation system can be used to raise valuable ornamental fish. After recycling for more than half a year, 15 fish survived well without changing water and sand.
There are several factors that affect the circulating water quantity in seafood pool:
1. The operation of the environmental system is blocked. Check whether the water pump is normal and the circulating pipeline is unobstructed immediately. If there is any fault, eliminate it in time.
2. The storage capacity exceeds the bearing capacity of the storage pool. It is necessary to reduce the storage capacity and strengthen the number of aeration and circulation.
3. The water quality deteriorated due to the death of seafood and aquatic products. Pay attention to observation at any time, and clear away those who are dead or disabled in time.
4. External pollutants are involved. After fully washing the circulating system, replace and add appropriate water for storage and maintenance.