Fritz Pro RPM Salt 180gal BucketFritz RPM Reef Pro Mix is manufactured using only the highest quality raw materials. Formulated by researchers and marine scientists, RPM contains all of the necessary major and minor elements of natural sea water that are utilized by living marine and reef animals. Correct pH and buffering capacity, essential minerals and trace elements have been added in precise ratios to ensure a correctly blended mix for the health and longevity of your livestock.