I had a frag with it and it came back quick and spread to other rock fast. Had to deal with it right away with aiptasia x. Went from 2-12 in a week. Granted its a new tank I was maybe 3 months in after cycling so I got rid of it right away. But hands off was a good approach for me with my new tank syndrome. After I just accepted the fact of massive amounts of Diatoms I stopped dosing and cleaning and soon after it all dissipated.