Brown algae on rock good or bad

[Connershawzz]

I just noticed this today after work , it definitely wasn’t there a few days ago. Any ideas ? And if it’s bad // how to get rid of it

 

[Colin_T]

Just looks like brown algae/ diatoms and is nothing to worry about unless it spreads rapidly and creates big sheets that smother everything. If it does that then it's blue green algae, which is different. At this stage leave it alone. If you don't like it, take the ornament outside and hose it off.

 

[GaryE]

It's neither good nor bad. It adds nothing, it subtracts nothing. Different algaes come and go, often attracted by the composition of the rocks you're using.

 

[MaloK]

If it takes it's nutrients from the rock itself, it wont spread far.

On the other hand if it's artificial decor, it takes it's nutrient from the water layer. It could become a different story.