1. Change black water and red water

(1) In summer, the color of pond water will suddenly change from green to black, red, and soy sauce. During this period, potassium persulfate can be used first, followed by the use of fruit acid water conditioners and amino acid fertilizers on the second day. If the weather is clear, Bacillus subtilis can be used in combination. Generally, after 3 days of use, the water color will gradually turn green. If you feel that the water quality has not changed much, you can use fruit acid water conditioners again on the third day.   

(2) If there is a change in the water quality of the pond and the heads of the fish float to the surface, the aerator can be activated to aerate them. If the fish do not gather towards the aerator, it indicates that the toxins emitted by the toxic algae in the pond will be detrimental to the growth of the fish, and in severe cases, it may even lead to a large number of fish deaths. During this period, a large dose of fruit acid water adjusting agent can be used first, followed by potassium persulfate. On the second day, amino acid cream fertilizer and fruit acid can be used to adjust the water quality.     

2. Treatment of oil film

(1) If the algae in the pond age and die, they will form a layer of oil film on the water surface. Most farmers think it is green algae or blue-green algae, but it is not. Generally, green algae and blue-green algae have phototaxis and will sink to the bottom of the water in the evening. They will float on the water surface during the day.   

(2) And the oil film will always float on the surface of the water and have viscosity. When there is a large amount of oil film floating on the surface of the pond, potassium persulfate can be sprayed on the oil film for about 2 consecutive days to effectively remove the oil film.     

3. The treatment of bottom heat in the pond: During summer evenings, hot air can be seen rising from the surface of the pond. This is mainly due to the presence of heat at the bottom of the pond, which indicates that fish heads will surface the next morning. Therefore, in the evening, potassium persulfate tablets can be sprinkled into the pond to not only improve bottom heat but also effectively prevent fish heads from floating.

4. Pond treatment after algae killing

(1) After using algae solubilizers or copper sulfate, dead algae will produce a large amount of toxins, which can cause shrimp, crabs, fish poisoning, and even direct death. On the second day of using these drugs, potassium persulfate can be used to regulate the water quality in the pond and alleviate fish poisoning.   

(2) Potassium hydrogen persulfate has a better effect on regulating water quality, but it should also be used according to the recommended dosage. Overuse can also lead to deterioration of the water body, causing serious impacts on shrimp, crabs, and fish.