Fish Feed Machine Knowleagde

The pH value of the water body refers to the negative value of the common logarithm of the hydrogen ion concentration in the aquaculture water body, that is, pH=-lg[H+]. In the process of aquaculture water quality management, pH management is an important part of water quality management. In the entire breeding cycle, an appropriate pH value is not only a necessary condition for the survival of the aquaculture object, but also an important reflection of the stability of the entire pond water quality. index. In aquaculture water bodies, the most suitable pH range for most fish and shrimp is neutral to slightly alkaline (ie 7.0-8.5), and pH<4.4 or pH>10 can directly lead to the death of aquatic animals. Generally, in aquaculture water, pH<6.5 or pH>9.0 indicates that the pH is beyond the suitable range for fish and shrimp to survive, and corresponding measures need to be taken to adjust.

1. Changes in the pH value of the aquaculture pond water and its influencing factors.
In intensive ponds, the pH change of the water body is mainly determined by the activities of phytoplankton, cultured animals and bacteria, and the decomposition of organic matter at the bottom of the pond. The daily pH value of the aquaculture water shows periodic changes, generally the lowest before the sun comes out in the early morning, and the highest during the day before the sun sets. The reason for the periodic changes is mainly due to the combined effect of the photosynthesis of planktonic algae and the respiration of pond organisms.

In the aquaculture water body, although the pH value of the aquaculture water body changes periodically every day, it can still maintain a relatively stable pH value. The relatively stable pH value in the water body of the breeding pond provides a stable water environment for the breeding animals and reduces the risk of stress caused by drastic changes in water quality factors. The aquaculture water has a buffering effect on the change of pH value mainly because there is enough alkalinity in the water body that can play a buffering effect. When the pH value of the aquaculture water body changes greatly every day, it indicates that the pH buffering effect of the aquaculture water body is weakening, and alkalinity needs to be supplemented in time. Generally, the HCO3-in the water body can be increased by adding baking soda or dolomite powder to the aquaculture water body. adjust.

2. The harm and control measures of excessive pH in aquaculture ponds
The hazards of excessive pH are mainly manifested in the following aspects:
1. Excessive pH will corrode the gills of fish, causing respiratory disorders in fishes, and long-term tissue lesions in the gills.
2. The pH of the water is too high, and the proportion of ammonia nitrogen in the water in the form of molecular ammonia increases greatly. When the pH exceeds 9.0, the content of molecular ammonia is greater than 35% (when the water temperature is greater than 25 degrees), which greatly increases the toxicity of ammonia nitrogen, and finally Affect the growth of farmed animals.
The control measures mainly include the following aspects
1. Change the water. For ponds with sufficient water sources and good water quality, the pH of the aquaculture water can be lowered by changing the water.
2. To control algae activities, you can choose copper sulfate and other algae killing drugs to kill some algae or use polyaluminum chloride and other flocculants to precipitate algae, reduce the abundance of algae in the pond to reduce the consumption of CO2 by photosynthesis, thereby controlling the pH Elevated.
3. Use microbial preparations to accelerate the decomposition of organic matter. The CO2 generated by the decomposition of organic matter provides more CO2 sources, eases the positive movement of the CO2 balance system, reduces the production of OH-, and uses certain probiotic species and algae at the same time Competitive relationship in nutrition to inhibit algae activity, reduce the consumption of CO2, and lower pH. In actual operation, EM bacteria can be used together with brown sugar and other nutrients to promote the growth and reproduction of beneficial bacteria to accelerate the decomposition of organic matter in water. Generally 500 ml of EM bacteria, with 2-3 kg of brown sugar, use one acre of water.
4. Use chemical methods to neutralize the OH- in the water body, mainly acetic acid (acetin) and citric acid, which are dissolved and spilled on the breeding water body, and the acid is used to directly neutralize the OH- in the water body to reduce the pH of the water body. This method It is mostly used when the pH of the water body is too high and urgent treatment is needed. In the actual use process, due to the influence of the water environment, the amount of use is relatively large and the cost is relatively high. Acetic acid (acetic acid) is mainly realized through its weak acid nature of acid-base neutralization reaction. In pond farming, vinegar is used to adjust the pH value. If the pH value is adjusted through acid-base neutralization reaction, the environment, microorganisms, impurities, water quality, etc. are not considered Factors such as the degree of electrolysis of acetic acid, etc., it is preliminarily estimated that it takes 40 kilograms of vinegar to adjust a pH of 8 per mu of water to a pH of 7, which is much larger in actual use.
5. Use water purifiers such as polyaluminum chloride and alum. On the one hand, use their chemical properties to react with hydroxide ions in the water to form colloids or precipitates to achieve the purpose of removing hydroxide ions in the water. The colloid produced by flocculation can also adsorb some phytoplankton, reduce the photosynthesis of phytoplankton, and achieve the purpose of lowering the pH of the water.

3. Harm of too low pH in aquaculture ponds and control measures
1. The hazards of low pH mainly include the following aspects:
On the one hand, a too low pH can directly affect the physiological activities of the fish, reduce the pH value of the blood of the breeding object, weaken the oxygen-carrying capacity in the period, and cause the fish to be physiologically hypoxic. The metabolism and growth of the breeding objects are inhibited.
In a low pH water environment, the content of molecular hydrogen sulfide in the water greatly increases. When the pH value is lower than 6.5, more than 70% of the hydrogen sulfide in the water exists in non-ionic form, which increases the toxicity of sulfide.
Since the most suitable pH for most aerobic bacteria is neutral and slightly alkaline, a too low pH will inhibit the decomposition of bacteria and slow down the decomposition of organic matter in the water. At the same time, a too low pH is not conducive to the nitrification reaction. , Resulting in the accumulation of ammonia nitrogen and nitrite, which are decomposition products of organic matter, and affect water quality.
2. Adjustment measures
For aquaculture water with a pH lower than 6.5, it is usually possible to increase the pH of the water by splashing quicklime with water. However, in seawater, there are too many calcium and magnesium ions in the water, due to the combination of magnesium ions and hydroxide ions. Combined with precipitation, it is much more difficult to increase the pH by splashing quicklime with water than with fresh water.
For ponds where the water source is convenient and the pH of the source water is appropriate, it can also be solved by changing the water.
Dredging the silt in the breeding gap to remove the excessive organic matter at the bottom of the pond to avoid the formation of anaerobic decomposition and acidification of the organic matter at the pond bottom.
Properly cultivate algae, promote the reproduction of beneficial algae, promote the positive movement of the CO2 balance system through the use of carbon dioxide by algae photosynthesis, and increase the OH- concentration in the water to increase the pH of the water body.

Four, summary
The proper pH value in the aquaculture water is not only necessary for the life of fish and shrimp, but the daily periodic changes of the aquaculture water are also a mirror reflecting the stability of the water quality, the abundance and growth of planktonic algae, according to the size and range of changes in the pH value every morning and evening Guiding the related operations of aquaculture water quality management, which is particularly common in the process of shrimp aquaculture.
In the process of transferring aquatic animals, although the pH values ​​of the water bodies before and after the transfer are within the normal range, the pH values ​​between the water bodies are too large. The drastic changes in pH after the transfer may cause fish and shrimp stress or even stress. Death, this should be paid special attention to when aquatic animals are transferred.