Nature's Ocean 12-Inch Coral Base Rocks for Aquarium, 40-Pound

Nature's Ocean Coral Base Rocks 40LBS (Packaged: 2 per case 12 Inch - 17 Inch)Nature's Ocean Base Rock is 100% premium all natural aragonite rock covered with naturally formed holes and crevices which makes for some very interesting and unique shapes and is easy to stack when creating a base for growing live coral or as an addition to existing coral-based ecosystems. This porous characteristic provides a natural biological filter as well as a perfect environment for denitrifying marine bacteria to grow and flourish, which effectively reduces nitrates in your tank.