Love to see a new tank progress! Thanks for the videos. Your tank looks like it’s progressing well. The brown diatoms will die off in time. Snails and hermits will help keep the algae down. If you want to add coraline algae get a piece of live rock with some on it and it should spread. If you’re an experienced reefer I’m sorry for the TMI I wasn’t sure.

I need coraline algea

algea grows on whites

You don't need that much light. It's insane how much you have. You don't even have corals. My fish tanks use only sun light from a side window so that I don't have to clean anything. And my coral tanks have way less light than you.