Willard Water Dark XXX Concentrate, 16 oz, Dr. Willard'sDr. Willard's Willard Water Dark XXX Concentrate Dr. Willard's Water XXX Concentrate contains about half the patented catalyst of the Clear Concentrate. However, the XXX contains fossilized organics (activated carbon, amino acids, readily available trace minerals and other desirable ingredients obtained from lignite. Lignite is the fossil remains of plants grown 50 million years ago). The XXX must be diluted according to instructions to ensure maximum