Caribsea Rift Lake Authentic African Cichlid Substrate 50 lb. bag. Finally substrates designed specifically for the advanced cichlid enthusiast. This new formula is derived from a rare dark colored calcium carbonate which will not only maintain an exceptionally high pH and carbonate hardness but also discourage cichlids from fading into the background. A must for healthy, vibrant African Cichlids (great for other hard-water freshwater fish too!). Available in 20 and 50 pound bags.