Principle of activated carbon filtration

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Principle of activated carbon filtration: The adsorption capacity of activated carbon is related to factors such as water temperature and water quality. The higher the water temperature, the stronger the adsorption capacity of activated carbon ； When the water temperature exceeds 30°C, the adsorption capacity reaches its limit and may gradually decrease. When the water quality is acidic, the adsorption capacity of activated carbon for anionic substances decreases relatively ； When the water quality is alkaline, the adsorption capacity of activated carbon for cationic substances decreases. Therefore, unstable pH of water quality can also affect the adsorption capacity of activated carbon. The adsorption principle of activated carbon is that a balanced surface concentration is formed on its particle surface, after which organic impurities are adsorbed into the interior of the activated carbon particles; the adsorption efficiency is very high at the beginning of use. However, over time, the adsorption capacity of activated carbon decreases to varying degrees, and its adsorption efficiency also declines as a result. If the water quality in the aquarium is poor and the organic matter content is high, the activated carbon will quickly lose its filtering capacity. Therefore, activated carbon should be cleaned or replaced regularly. The size of activated carbon particles also affects the adsorption capacity. Generally speaking, the smaller the activated carbon particles, the larger the filtration area. Therefore, powdered activated carbon has the largest total surface area and the best adsorption capacity, but it can easily flow into the aquarium with water, making it difficult to control, which is why it is rarely used. Granular activated carbon, due to its granular structure which makes it less prone to flowing, does not allow impurities such as organic matter in water to easily clog the activated carbon filter layer. It possesses strong adsorption capacity and is easy to handle and replace. The adsorption capacity of activated carbon is proportional to the time it spends in contact with water; the longer the contact time, the better the quality of the water after filtration. Note: The filtered water should flow out of the filter layer slowly. The new activated carbon should be washed thoroughly before its first use; otherwise, ink-black water will flow out. Before installing the activated carbon in the filter, a layer of sponge 2–3 centimeters thick should be placed at the bottom and top; this serves to prevent large particles such as algae from penetrating inside. After 2–3 months of use, if the filtering efficiency declines, the activated carbon should be replaced, and the sponge layer also needs to be changed regularly.