Harmfulness: There are a lot of residual baits, feces, dead biological remains and other organic substances in the bottom mud of shrimp culture, and the bottom mud keeps accumulating in the pond. Many organic substances contained in the sediment consume a lot of oxygen during the action of spoilage bacteria, which makes the whole pond, especially the bottom, anoxic, resulting in black and smelly water, and produces toxic substances such as ammonia nitrogen, nitrite nitrogen, methane, hydrogen sulfide, etc., which makes aquatic animals float on their heads due to hypoxia, prone to disease, slow growth and high mortality.

Advantages: it is beneficial to have a layer of silt with appropriate thickness at the bottom of the culture pond, and the silt contains a lot of nutrients. These nutrients need to be transformed by beneficial microorganisms before they can be absorbed by algae and become useful fertilizers. Silt with a certain thickness can play the role of supplying and preserving fertilizer and adjusting the sudden change of water quality in buffer pond.