1. Biological methods
(1) Stock a certain number of filter-feeding fish.
Although cyanobacteria are not easy to digest, due to their larger particles, they are more easily ingested by filter-feeding fish. Therefore, stocking a certain number of filter-feeding fish can help delay and hinder the growth of cyanobacteria. The fish options available include silver carp, silver carp, white crucian carp, etc. Practice has shown that silver carp with a tail weight of more than 200g has a significant inhibitory effect on cyanobacteria. When the total amount of silver carp reaches 100Kg/acre, cyanobacteria will basically not explode.
(2) Regularly use high-quality microbial preparations.
First, use Bacillus, lactic acid bacteria, etc. to degrade excess organic matter in the pond water. These micro-ecological agents compete with cyanobacteria for ecological space, stabilize the water body, and promote the growth of beneficial algae such as green algae.
The role of Bacillus has been recognized. However, we often find that different products have different effects when using them. Some products are effective when used in small amounts, while others are not effective even when used in large amounts. Why? Because the core technology of microbial preparations lies in the quality of strains and the number of strains. Many farmers mistakenly believe that more weight means more quantity. In fact, this is not the case. Advanced fermentation technology and preparation technology can make the total number of bacteria in each gram of product reach more than 50 billion. It is difficult for ordinary small manufacturers to achieve this due to technical and equipment constraints. At the same time, the quality of the bacteria determines the effectiveness of the product. Bacillus is a general term for spore-bearing bacteria, and there are hundreds of species of Bacillus. Some are suitable for human intestines, some are suitable for water quality improvement, and some are suitable for garbage disposal. In other words, not all Bacillus species are suitable for aquaculture. Therefore, it is recommended that you choose high-content products when choosing products, because only large manufacturers can make high-content products, and they will also select strains suitable for aquaculture from the strain library for production.
(3) Introduce fine algae to inhibit the growth of cyanobacteria.
Chlorella is an excellent algae species, the most common and most effective product in the algae supplementation process. However, it is difficult for many farmers to achieve the expected results after purchasing chlorella. Why? In fact, the number of live chlorella algae species purchased through general channels is very small. The suitable temperature for the growth of chlorella is 20~30℃. At this temperature, chlorella will reproduce rapidly, grow and die. The entire life cycle is about 12 days. Therefore, at room temperature, the life cycle of chlorella is shorter. The entire process from manufacturer to dealer to farmer takes a long time. The latest technology at present is to super-concentrate chlorella, then store it refrigerated at 4 degrees Celsius, and transport it in a cold chain during transportation. In this way, after farmers receive the super-concentrated chlorella delivered from the cold chain, they can promptly store it in the refrigerator and dilute it directly when using it, which is both convenient and effective.
2. Engineering algae removal
(1) Water diversion and water change
For ponds containing more cyanobacteria, change fresh water frequently and in large quantities, which can be diluted The concentration of cyanobacteria can also dilute the concentration of toxic substances such as phycocyanin secreted by cyanobacteria, promote the growth of other algae, and maintain the dynamic balance of the entire ecosystem. It can reduce the key water quality indicators of eutrophication, such as total phosphorus and organic matter pollution indicators, and permanganate index concentration.
(2) Enclosure and interception
Can only limit the expansion of cyanobacteria breeding area, but cannot achieve the effect of controlling cyanobacteria.
3. Direct physical algae removal
(1) Manual fishing
Manual fishing to harvest algae is the most direct way to control the total amount of cyanobacteria and can effectively reduce local Algae bloom disasters, while harvesting algae, also play a role in exporting nutrients and reducing algae toxin pollution caused by the death and decomposition of algae. Manual salvage collection methods are backward and time is limited, resulting in low efficiency and high cost.
(2) Other methods
For example, using activated carbon adsorption is very effective in removing algae and algae toxins. However, organic matter in the water will affect the adsorption activity of activated carbon. In a large area, It is difficult to recycle and regenerate when used internally, and the cost of disposal is very high.
(3) Thoroughly clean and disinfect the pond and add fresh water without cyanobacteria
Since cyanobacteria are more competitive than other algae, control measures focus on prevention and prevention of serious diseases. Yu Zhi. Thorough pond cleaning and disinfection can effectively kill cyanobacteria, reduce the number of algae species, and avoid large-scale outbreaks. Avoiding the introduction of cyanobacteria with added water also has positive significance for control.
4. Chemical methods
A low nitrogen to phosphorus ratio is conducive to nitrogen fixation by cyanobacteria, while a high nitrogen to phosphorus ratio is conducive to the reproduction of green algae. Some foreign scholars believe that when the nitrogen-phosphorus ratio is close to or equal to 16:1, the outbreak of nitrogen-fixing cyanobacteria can be effectively controlled.