With caribsea sea pure you can stop wondering if your salt mix lives up to real saltwater stop worrying about harmful impurities in your tap water sea pure is real seawater and contains all the major and minor trace elements found in natural seawater in correct proportions and at the proper ph no potential harmful pathogens no nitrates or phosphates no harmful organics no artificial perservatives or chemicals sea pure is simply seawater as nature intendedideal use for small aquariums tha