Treatment methods for turbid water in loach ponds during the rainy season
Every year in April and May, this season sees the northeast monsoon shift to the sub-southern monsoon season, with relatively large temperature fluctuations and increased rainfall, which often causes loach ponds in the middle of aquaculture to have their water color change from brown or green to turbid, appearing milky white. The main causes of this situation are sudden weather changes, death of phytoplankton, resulting in oxygen deficiency, or explosive reproduction of zooplankton, which feed heavily on algae. If the pond transparency is relatively high, the number of phytoplankton reproduced cannot meet the needs of zooplankton, and they will eat all the phytoplankton, thus losing the original water color and becoming turbid. This is because the water color and transparency in the pond are determined by the species and quantity of phytoplankton in the pond.
The harm of turbid water lies in causing oxygen deficiency in the pond. This is because the main source of oxygen in the pond is the photosynthesis of phytoplankton. According to reports, the oxygen content produced by phytoplankton photosynthesis can account for 91.3%-100% of the dissolved oxygen income in seawater ponds, while the diffusion effect of the atmosphere accounts for only 5.3%-7.8% of the dissolved oxygen income in ponds. Turbid pond water means that there is very little phytoplankton in the pond, so of course there is very little photosynthesis, and the oxygen produced is naturally reduced.
It is precisely because June and July are seasons of overcast and rainy days, heavy rain and torrential rain. In this kind of weather, sunlight is weakened, photosynthesis is reduced, and the oxygen supply is also reduced. Under such severe weather, if daily management work is not strong, loaches are prone to disease. Loach farmers lacking scientific knowledge are at a loss about how to deal with this water color. In fact, once the mechanism of its occurrence is clearly understood, solving the problem of turbid water is not difficult. In addition to reducing the oxygen supply and affecting the respiration and growth of loaches, turbid water can also lead to deterioration of water quality. This is because there is a large amount of loach excrement, residual bait and biological corpses in the pond sediment. If these substances are under conditions of sufficient oxygen, oxidation reactions easily occur, and harmful substances such as ammonia nitrogen, nitrite and hydrogen sulfide become fewer and fewer. Under oxygen-deficient conditions in the pond sediment, reduction reactions increase, and harmful substances become more and more numerous, causing stress in loaches, and disease arises from this.
Turbid water has the following treatment methods:
1. Use disinfectant drugs to kill part of the zooplankton. Quicklime is commonly used, at a concentration of 20 ppm (20 grams per cubic meter of water; if the water depth is 1 m, use about 13 kg of quicklime per mu). First dissolve the quicklime in water, add water to dilute, and splash it evenly over the whole pond. After using quicklime, the water will become somewhat clearer. Other disinfectants can also be used, but their concentration must be premised on the safety of the loaches.
2. Stop feeding for 1-2 meals. The purpose is to make the loaches hungry so they compete for part of the zooplankton, reducing the number of zooplankton and making it easier to cultivate algae.
3. Change 5-10 cm of water. The purpose of changing the water is to supplement algae species. Because there are very few algae in turbid water, it is more difficult to cultivate algae when there are few algae species, so the content of algae species must be increased to facilitate fertilizing the water, so that algae can be cultivated in a relatively short time. If an adjacent pond you are cultivating is raising shrimp or fish, and the water color is also good, with no other diseases, you can pump some over to supplement algae, and the effect is also very good.
4. Fertilize immediately. Try to use inorganic fertilizer rather than organic fertilizer. According to feedback from many loach farmers in recent years, using organic fertilizer to fertilize water gives loaches more opportunities to develop disease.
5. Use single-cell algae growth hormone. It is formulated according to the special nutritional requirements of single-cell algae and contains highly active nutrient elements such as nitrogen, phosphorus, potassium and silicon. It is beneficial to the reproduction of single-cell algae, has a long effective period, and generally only requires one-time water fertilization for loach farming. The dosage is also small. Generally, when the water depth is 0.6 m, only 1-1.5 kg per mu is needed. The price is also cheap, usually 6-8 yuan per mu. It is even simpler to use; just add water to dissolve it, dilute it, and splash it over the whole pond. It also takes effect quickly. Within 24 hours the water color will turn brown and green, and within 48 hours it will achieve the expected effect.
Water fertilization should be carried out on a sunny morning; do not fertilize water on cloudy or rainy days.
6. Use microbial preparations in combination, such as Bacillus, photosynthetic bacteria and EM bacteria, etc.
7. In addition, applying some zeolite powder and reasonably using aerators will give better results.
In short, turbid water is extremely harmful to loaches in the middle of aquaculture. When it first appears, the loaches do not show obvious abnormal symptoms, but if it is not treated in time, the consequences are unimaginable. Be sure to detect it in time and treat it in time, promptly change the water color and transparency, maintain the ecological balance of the aquaculture water body, and prevent the occurrence of loach diseases.