1. Fertilization Fertilizers for winter fertilization can accelerate the reproduction of phytoplankton. Phytoplanktons are the main primary producers in the pond ecosystem, and they are the main force for biological aerobics. They consume large amounts of carbon dioxide and nitrogen during their growth and reproduction. , phosphorus and other nutrients and inorganic salts. For overwintering pools where nutrient content is extremely low after long periods of inability to rehydrate or replenish water, inorganic fertilizer should be applied soon after the ice is sealed. With 1.5 mg/l effective nitrogen and 0.2 mg/l effective phosphorus, nitrogen and phosphorus were separately hung under ice.
Second, control the zooplankton over a few days before winter with a 1-2 mg / l crystal trichlorfon Quanchiposa. Use trichlorfon 1 mg/l to kill the sword leeches and 2 mg/litre to kill rhinophytes. During the ice-sealing period, it was found that the zooplankton in the pool had too much breeding to hang the trichlorfon under the ice.
Third, make up the new water over winter pond if you can maintain a certain water level, do not have to pay water. When the water level drops more, it is timely to replenish the water, but avoid a lot of replenishment at once, so as not to inhibit the growth and reproduction of plankton.
Fourth, snow removal only adhere to the timely removal of snow, water under the ice can have enough light to ensure that photosynthetic ice under the phytoplankton. Whether it is clear ice or black ice should be timely snow sweeping, the larger the better the snow area. If it cannot be cleaned completely, it can be swept into snowballs. It is better to go north and south. The area of ​​snow sweep should be over 40% of the pond. It is better to have a small snow thrower for fisheries that have a large wintering area. It should be pointed out that even in the case of black ice, the oxygen production capacity of the surface water is considerable. It is 70% of the clear ice. As long as the depth of the pond is appropriate, adequate plant nutrient salts can be ensured, and the photosynthesis under the ice can also be achieved. Produce enough dissolved oxygen to make the fish safe for winter, but it is better to re-open the clear ice and ensure the photosynthesis of phytoplankton under the ice. There are many factors that affect biological oxygenation, and the rate of biological oxygenation is relatively slow. A certain amount of chemical oxygenation drugs (such as quick-acting floating head spirit) or mechanical oxygenation equipment should be prepared for emergency use.
Oxygen-enhanced medicines are available in a pond with an average depth of 1 meter under ice and can be used at 1 kg/mu. Minimize the aerator, because the aerator stirs the water body, so that the fish consume the energy in the body, the water body turns over and turbid, and it will increase the oxygen consumption factor.
Fifth, the control of water toxic factors The main toxic factors of water are nh3, no2-, ph and h2s, etc. They all reduce the oxygen capacity of the fish's resting blood or affect the normal breathing of fish, reduce the resistance of fish to overwintering and resist the environment. Change ability. During the wintering period, the water body should be frequently tested and prevented in time. When the ph value of the water body is less than 5, the whole pool will be poured with lime slurry to 40-50 kg per mu; when the nh3, no2, and h2s are too high, the release and transformation will be accelerated by changing the water or opening the aerator. Higher nh3 use 40-50kg zeolite powder per acre to reduce the concentration of nh3; if no2-high use of salt to reduce no2-toxicity to fish, 5-10kg per mu; if h2s is high, use feso4 to release 0.3-0.3mu per mu. 0.5kg.
In short, the use of some comprehensive water quality improvers during the winter period can improve the water environment, especially for the bottom water body, and can solve the phenomenon of winter fish dead due to water changes.

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