Questions - Need some input

Hi i want to ask how to removed this brown algae on my rocks and whats causing it to grow?
this is not the actual pics just found it on the web but it look like this.


Bristle worm are reef safe or not? do they harm other LS?

Not the actual pics but look like this one and i think the lenght is 4-5 inch in L.

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Hi! every one im planing to built a shallow rimless reef tank, and im choosing 2 sizes
1. 38X25X15 (L,W,H) 2. 35X35X15 (L,W,H)
I'm just wondering if 1 (150w DE MH) can support the L and W of my tank? im planing to have a LPS, Montipora Capricornis, zoas, clams and softies. Thanks!

Hi to all i have a 30g cube mixed reef 8 months old. i was planing to replace my old rock scape and sand to new rock scape and sand. the plan is i will remove my corals and LR and shipon my sand, then i repace it with new sand and put the new rock scape and place all my corals. do i need to cycle again my tank for replacing all my LR and sand to new one? TIA!