No one asked how long you're running the lights. How long? Do you have coral? If not then you may not need the high output light. Does the tank get direct sunlight? Are you using a protein skimmer? Could you be over feeding? How much and how often do you feed? What kind of food do you feed? Do you have enough circulation? When you do waterchanges do you vacuum or desilt? Are you running carbon? These are all pertintent questions.
Withput addressing the cause you can only treat the symptoms. It's like trying to heal a gunshot wound with gauze.
