Is this brown stuff on the bottom of my glass diatoms? I am on my seventh week of my cycle no lights on at all or skimmer . This week I will add cope pods and coralline algee . Zero nitrites and ammonia. Please if anyone can comment on what steps should I take I would like to add a clown fish in two to 3 weeks from dr. Reefs quarantined fish . Thanks I am a noob go easy on me please. Also can I just suck all that brown stuff up when I change the water?