Marine Depot carries it too. Melev tried some in his tank, and said it really didnt make a difference. But sometimes, pictures cant be omitted, and I've seen some amazing european tanks that have run it. Whether its from the probidio or something else, that is up for debate, but it is impressive nonetheless. From what I understand it is a lot iof strains of diofferent things, including some pseudomonas species. I dont know if any of you know, but some psuedomonas are nasty critters, so it was enough to steer me away.