The main sources of
dissolved oxygen in ponds are photosynthesis of phytoplankton, mechanical aeration and dissolved oxygen in air. Dissolved oxygen consumption is mainly caused by the respiration of plankton and the decomposition of organic matter in water. In addition, dissolved oxygen in ponds is also affected by many factors such as light, wind and air pressure and plankton and water quality. Although there is a certain law of change, but only rely on experience cannot accurately judge the dissolved oxygen content in the pond, misjudgment will have a high risk!
The change of dissolved oxygen in the bottom is an important index to reflect whether fish and shrimp are healthy or not. It can provide scientific reference for the management of sediment and water quality. To master the change rule of dissolved oxygen in water with oxygen measuring instrument, we should record dissolved oxygen four times a day: the first time is at 05:30 a.m., the lowest stage of dissolved oxygen in a day; the second time is at 08:30 a.m., which can be used as the basis for starting feeding; the third time is at 15:30 p.m., the highest stage of dissolved oxygen in a day; the fourth time is at 23:00 p.m. It can be used as a basis for all oxygen increasing machines. Through long-term observation and record, we can predict changes in sediment quality and water quality and control ahead of schedule.
The change of dissolved oxygen in the bottom should not exceed 7mg/L in one day, which is an important indicator of the health of fish and shrimp. The substrate and water quality are good and suitable for the growth of fish and shrimp. Special attention should be paid to: in the early stage of culture, if harmful algae are produced due to the imbalance of algae phase, although the bottom dissolved oxygen changes normally, fish and shrimp may also be sick. Therefore, in the early stage of culture, microbial preparations should be put regularly to remove organic matter from the bottom of the pond and cultivate beneficial algae phase; in the middle and late stage of culture, microbial preparations should be put regularly to remove organic matter from the bottom of the pond and to degrade nitrite and ammonia nitrogen, so as to reduce oxygen deficiency induced by organic matter and cultivate beneficial bacterial phase and algae phase.