Hi
I just finished getting my tank rid of dinos after 9 month battle. The first mistake I did was to think they were diatoms and went about doing everything to treat them...changed RODI Unit, changed bulbs, changed salt, changed everything...nothing helped.
All my inverts eating the dinos died, my tang picking on rocks covered with dinos died..
They would go away when I turn my lights off for 3-5 days and then come right back a week later with lights on. I finally got tired and got rid of all my sand. Yes, removed all the rock, fish and coral...sucked all the sand out..Brushed my live rock clean...washed it in fresh salt water....got new sand from store and cycled my tank...now they are gone......and it has been 4 months since I last saw them....good luck...the one thing you need to do is to make sure its dinoflagellates and not diatoms.
Hope that helps
Vishnu