Water purifying agent is harmful to fish. The main components of the water purifier are polyaluminum chloride, polyaluminum ferric chloride, aluminum sulfate and ferrous sulfate. Although the water purifying agent can coagulate and precipitate impurities, it cannot be decomposed. Aluminum sulfate and ferrous sulfate in the water purifier have irritating damage to the epidermis mucosa of fish eyes, while aluminum ions and trivalent iron are toxic substances. In addition, the components of the water purifier have colloidal properties. If used for a long time, they will condense in fish gills, which is easy to form gill blockage.

It has the advantages of good water purification effect, fast water purification speed, weak acidity, inorganic, high safety and no secondary pollution, and belongs to green environmental protection products. Natural materials with adsorption capacity are used as raw materials, which has strong purification effect and can remove heavy metals from water. The treated raw water is not affected by water temperature and pH value, and has a wide application range. The treated water is very transparent and can be reused.

Flocculant is the most commonly used flocculant in water purification agent. Flocculants include inorganic flocculants and organic flocculants. Inorganic flocculants are high-valent metal salts, such as aluminum sulfate, ferric sulfate, ferric chloride, titanium tetrachloride, inorganic acid and alkali. A typical example is that some mineral processing plants add lime to the concentration tank to accelerate the settlement of concentrate, improve the efficiency of concentration and filtration and reduce the loss of metal.