O.K. ......let's examine this. You have 384 watts over a FOWLR tank. Your primary producers are algae....you have no corals to utilize this light. The temp alone will not grow algae. NOTHING by itself will grow algae in a tank. It is a cooperative effect between light and nutrients. Low nutrients, high light, little or no algae growth. Low light, high nutrients, same thing. You have a fish only system, correct? Now you have bright lights. High light and high nutrients. But "no" you say. "i have tested my parameters and all look fine." BUT. Keep in mind that without that algae in there....your tests would show higher readings. The nutrients are testing low because they are bound in the algae. Do you want this to be a reef tank? If not....don't worry too much about the sand critters. Note I said too much...you still want some in there. If it is to be a FO...then put on a UV sterilizer. Put Caulerpa in the tankand let if grow if it will. Caulerpa prolifera will be best for a FO. It will utilize the nutrients too. Also, keep in mind that algae uses for food things you can not test for as well, not just NO2 and NO3. I would turn on only two of the lights, one on each side. Turn the others on if you put caulerpa in there. Good luck.