CaribSea’s A.R.K.™ is the first complete refugium kit for marine and reef aquariums which caters to the growth of these hard to obtain, hard to produce, natural foods. Only the A.R.K.™ contains substrates from .1 mm to 125 mm long axis, creating a haven for not only denitrifying and nitrifying bacteria, but also benthic organisms such as copepods and decapods. The larger macro-pores created by the variety of calcium carbonate rubbles form a cryptic zone to encourage the growth of water purifying sponges and larger invertebrates such as shrimp, worms, and serpent stars. Also inside, a 5 lb bag of CaribSea’s Mineral Mud™ to be used around Caulerpa, Halimeda, and other macro-algae plantings or anchors. The A.R.K.™ also contains a 4 ounce bottle of PurpleUp™, the only patented coralline algae accelerator, and an 8 ounce bottle of Aquabiotic™ to aid in the start up of necessary water purifying bacteria.. You will also find an 80 gallon dose of BioMagnet™, which clarifies water and places bacteria within the substrate and filter media as needed. CONTENTS: (all in 5 gallon bucket) 40 lbs of Arag-Alive!™ Bahamas Oolite aragonite sand, .1-1.0 mm. ; 10 lb. of natural calcium carbonate rubble 25+mm; 5 lb. of Mineral Mud™; 1- 8 ounce AquaBiotic™; 1- 4 ounce Purple-Up™; 2- 40 lb. dose packs of BioMagnet™.