The most revolutionary aquaria water stain remover that is safe to use and with fast results. • Ocean Free Super Zero Color can be placed in any filtration system that uses a filter box or canister • Just lay the Ocean Free Super Zero Color pack in the filter where there would be constant water movement to achieve better results • Ocean Free Super Zero Color can also be place directly inside the fish tank where there is water circulation • Do change to new pack after 1 month period or when the staining of color comes back