Please help me to identify if this is algae?

Hello all the experts out there. I'm a fresh newbie to the hobby, but not the forum because I've been followed this forum for so long before I got my tank.
I bought my tank used with LR and LSand included.
What is it the green thing sticking out from my LR please?
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What are the brown spots on my live sand? Is it brown algae? It was not there on the 1st day I got my tank set up. It appeared like 2-3 days after I got everything running in my tank.
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Thank you in advance.

 

Hello and Welcome to 3reef.

The brown is diatoms, part of a normal cycle. Diatoms will die back as the silicates are used up. The green has the potential to be Byropsis and will need an intervention. Or it could simply be Green Hair Algae the will resolve as long as you are using RO/DI water.

 

the first pic does look like green hair algae, but a close up shot of it would help be sure.

 

Thank you y'all for the replies. Here are a few more close-up pics of the algae. [/URL][/IMG]
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Bryopsis also known as devil weed.You can do a total tank blackout for a few weeks and or raise the Mag. to 1650. It looks like it is only on one rock so I would forget the blackout and mag. in favor of removing the infected rock and bleaching it. Manual removal of it also helps but can be difficult.