Aquaculture you need to know several water quality conditions

The main indexes to measure the quality of aquaculture pond water are: dissolved oxygen value, pH value, ammonia nitrogen and nitrite. These indicators should be checked frequently to detect the pond water quality, and based on this, the pond water quality control. These conventional indicators are analyzed as follows to help farmers clearly understand and apply them to pond water quality management.

1. Dissolved oxygen

Oxygen is not only necessary for our human survival, but also the basis for the survival of fish, shrimp and shellfish in the water. Dissolved oxygen content in water is low, fish and shrimp will float head, when the dissolved oxygen is low to the asphyxiation point will cause fish and shrimp asphyxiation. The suitable dissolved oxygen of fish is 5mg/L, and that of shrimp is 3mg/L. The oxygen in the water mainly comes from the photosynthesis of algae, accounting for about 70% of the dissolved oxygen in the water, followed by the air dissolved into. The main oxygen consumption was respiratory consumption of main fish and shrimp, accounting for 20~25%. The substrate consumption is about 25~35%; The consumption of other bacteria, plankton and organic matter fermentation in water accounts for about 45~50%.

Long-term not dredging or did not change the bottom of the pond, the bottom acid rancidity, fever, smelly oxygen consumption will rise to more than 50%. Therefore, in our breeding process, if we want to maintain the dissolved oxygen demand of cultured fish, we should control it from the root according to the source and consumption of dissolved oxygen. Scientifically fertilize the water, adjust the algal phase, change the bottom regularly, reduce the oxygen consumption at the bottom, control other plankton in the water, reasonably open the oxygenator, add new water, etc.

2. PH (PH value)

pH value refers to the level of pH in water. The difference of pH can be divided into strong acid pH<0.5, weak="" acid="" ph="" neutral="" basic="" and="" strong="">10.0. Most natural water is neutral to weakly alkaline, the pH of fresh water is 6.5~8.5, the pH of seawater is 8.0~8.5, and the appropriate pH of freshwater aquaculture ponds is 7.5~8.5. The change of pH in aquaculture ponds is mainly caused by photosynthesis and respiration. Photosynthesis increases the pH of the water by consuming carbon dioxide (producing oxygen), and respiration lowers the pH by producing carbon dioxide. The change of pH can make the blood pH of aquatic animals change correspondingly through the osmosis and respiration of hydrogen ions, thus destroying the oxygen delivery function. Too strong alkaline often directly corrodes the gill tissue, resulting in respiratory disorders of farmed animals.

The change of pH will also affect the existence form of many substances, especially the existence form of some toxic substances, thus changing their toxicity and indirectly affecting the life activities of aquatic organisms. The change of pH has an obvious effect on the larva of aquatic animals. pH regulation is also an important part of water quality regulation. Too much silt in the pond will increase the acidity of the water.

3. Ammonia nitrogen

Ammonia-nitrogen ₃ is a general term for free ammonia (NH ₃) and ammonium (NH4+). Ammonia nitrogen is a nutrient element in water, and its source is mainly produced by decomposition of nitrogen-containing organic matter and decomposition of aquatic organisms, residual bait, feces and biological remains. Excessive ammonia nitrogen can lead to eutrophication of water, poisoning of aquatic animals such as fish and shrimp, resulting in increased surface mucus, bleeding, loss of appetite, inhibit their growth, and even death in severe cases. The ammonia nitrogen content of aquaculture water shall not exceed 0.2mg/L.

The methods to prevent ammonia nitrogen from being too high in water include: reasonable collocation and density of breeding varieties; When clearing the pond, remove the excess silt from the bottom of the pond; Regularly use oxidizing products (such as "Golden Shield all-powerful", "Platinum shield all-powerful", "platinum source shield-bottom shield", "Platinum Fudijian", etc.) to decompose the bottom residual bait feces; Add new water or change water regularly to cultivate beneficial algae fungi; Scientific use of oxygenator, so that water dissolved oxygen sufficient. When the aquaculture water ammonia nitrogen is too high, you can use "Junduxiao" or "Jiedu should Jingling" detoxification, use "Amgen great energy oxygen" oxygenation, and then regulate the water quality.

4. Nitrite

Nitrite is a kind of inorganic compounds containing nitrogen which exists widely in nature and is one of the products of water nitrogen cycle. The concentration of nitrite in breeding ponds should be controlled below 0.05mg/L. The high content of nitrite in aquaculture water will cause poisoning of fish and shrimp. The principle is that nitrite will oxidize the ferrous hemoglobin in the blood of fish and shrimp into methemoglobin, thus inhibiting the oxygen carrying capacity of the blood, leading to some metabolic dysfunction and physical decline of fish and shrimp. At this time, fish and shrimp are very prone to disease, and severe cases may result in a large area of disease outbreak and death.

Fish and shrimp live in high nitrite water for a long time, it will cause chronic poisoning, fish and shrimp food intake decrease, gill tissue lesions, dyspnea, disturbance. Therefore, in the process of breeding, we should strictly control the nitrite in the water body. The key factor to control nitrite is to maintain sufficient dissolved oxygen in water, promote the transformation of nitrite to nitrate, and reduce the concentration of nitrite. Therefore, in the usual management process regularly add new water, open oxygen machine and other work, once nitrite exceeded the recommended use of Amgen "nitrite speed net", "nitrite net", "nitrite speed down", and then water transfer.

5. Others

In addition, the evaluation indexes of pond water quality are as follows: transparency, temperature, alkalinity, hydrogen sulfide, chemical oxygen demand and electrical conductivity. These indicators are mostly used for academic communication, and rarely detected in actual production, which will not be described here. The above indicators are the indicators that farmers should pay attention to in the process of breeding. The water quality of these indicators should be tested regularly, the water quality should be adjusted in time, and the water quality should be maintained within the normal range, so as to reduce unnecessary losses.