Aqua One Premium Carb is an activated carbon that is Phosphate free, and can be used in all types of filtration systems! Aqua One Premium Carb removes dissolved organic waste from aquariums as well as dyes. Premium Carb has a large surface area which absorbs minute particles that are held in suspension in aquarium water. Water passes through the carbon, the carbon then traps small particles in its pores before it is removed by the user. It is suitable for both freshwater and saltwater aquariums.