Reeflowers Iceland Black Sand is a clean and natural sand specifically produced for aquariums that does not release any constituents into the water does not cause any change in gH kH and pH values does not contain any heavy metal or toxic substances. Cleaned and sterilized using ultra-filtration techniques and activated carbon no chemical treatments used and does not contain any synthtic components. Perfect for use in every kind of soft water aquarium. Including Discus aquariums!