Chrysophyte was a tough battle in my tank.
I suctioned out every 2 days, they grew back within a day.
I tried metronidazole which did not work.
Dosed bottled bacteria, did not work.
Things that I believe helped solve my issue:
Increased nutrients (no3 5-10 and PO4 0.05-0.1), a little help.
Manual removal by suctioning them into a filter sock in the sump every few days.
Vibrant helped more, but still did not solve.
Added more live rock and sand from the Keys, pretty well finished them off while doing everything else as a combo.