Polyaluminum chloride put in the water, the water body to remain stationary state 5 to 6 hours to absorb sewage: adsorption time is not appropriate, will have a counter-ion effect, it is difficult to aggregate. 3, which led to the floating or unsinkable sediment. Poor regulation of pH can also cause this to happen; dosage is too high. Dosage is too small, prone to water disturbance, similar to the air convection, is the formation of the wind. Water temperature changes too fast, will lead to water in the upper and lower water temperature is different, precipitation floating. 2: water quality problems. Rapid changes in water temperature or pH outside the range of use of polyaluminum chloride can lead to precipitation or floating of polyaluminium chloride, resulting in the formation of small and still some suspended solids can not form a precipitate: polyaluminum chloride Improper dosage: 1 PAC precipitation sinking or floating for the following reasons