HOBBY Carbon Aktiv (Active)A powerful filter material. It very efficiently removes residual medicines, chlorine, even odours and, above all, contaminants that result of organic waste. Carbon should not be used while the fish are under medical treatment. A very practical reccomandation is to put the filter material in the HOBBY Net filter bag. highly effective in removing residual medicine, chlorine, organic waste, and odours do not use during medical treatment of fish use for a