Contains: 416000 ppm Calcium,577000 ppm Carbonate,3300 ppm Strontium,1400 ppm Magnesium,56 ppm Potassium. About 70 pounds per cubic foot ,Calcium reactors have evolved into several types that require different media sizes. Because of this,ARM Coarse for rapid up flow type reactors.This coarse grade of ARM will prevent the clogging and upkeep associated with fine media and these reactors.A.R.M is low in phosphates and silica ,as exclusion of gastropod shells, so it wont add any unwanted elements. The product is 10-15mm in size which allows for the best carbon dioxide penetration, and the best results The media contains a high amount of Halimeda Incrassata, a pure aragonite that is used in laboratories.