What is it, brown coralline algae?

[shingo43]

Setting up a new tank and see the brown dots of the rock, just want to confirm what is it?

 

[GimpyFin]

Most likely it's diatoms starting to show, especially with it being a new tank.

 

[scooter31707]

Yep, I agree with the beginning stage of diatoms. It's very normal in new tank setups. It will eventually go away on it's own.

 

[reef thief]

You're good. Just keep on keepin on nice and slow like.

 

[75mixedreef]

It is not a problem. If your tank is cycled then you could just add some snails to clean it up.

 

[AlSimmons]

Just to make sure it is in fact Diatoms you might want to get a brush and see if it comes off the rocks fairly easy. If not it might be another type of algae. Unfortunately I can't remember the name of it right now, but it does start off as small brown spots like that.

 

[shingo43]

Thanks guys, they don't look like diatoms, I had diatom bloom in the beginning of the cycling but they went away after I introduced cucs.
The tank was setup in Aug so it has been a while and the brown algae are not going away nor expanding. Now the purple coralline algaes are started to grow on the rocks too so I have lots of colorful dots on my rocks

 

[scooter31707]

It could be the start of coralline algae. I have heard it can come in different colors. IME, the coralline started out greenish/purplish color.