Do you have yellow aquarium water? Does fish tank smell get you down? Struggling with nitrates or aquarium algae? Try granular activated carbon. Activated carbon is heated and treated to increase its strength. Granular carbon is pelletized to reduce ash. Good aquarium carbon won’t leach phosphates or waste back into the fish tank. Carbon can be placed in a filter media bag in a filter at a high flow rate, but aquarium carbon does especially well when it is placed in a fluidized media reactor. Carbon can also be placed in a bag in a filter sock or sump but is less effective.