All the diatom in my tank just gone few days ago. They have been in my tank for 3 weeks time. It really annoyed. What I do, just leave it and buy some Turbo snail and sand shifting starfish to help me clean it up. I didn't turn the light off, just let it run 8 hours a day. Besides, I had gone through bryopsis algae bloom in my tank during diatom bloom. But now, everything settle down. Bryopsis gone, diatom gone. =D