What is this algae!

[EddieJ123]

I have these things growing on the side of my tank and I'm wondering if they are bad or good.


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[bribo12]

Coralline algae


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[54seaweed]

the back and 2 sides on my tank are black ,I let it grow on those 3 walls ,if it gets on the front glass I scrape it off ,
but since your sides are clear I would probably scrape it off ,
thats why Ive done this

lighting stays more direct on corals and hides all the growth on walls and tank seems brighter

 

[Sniperhank]

Coralline algae


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Either that or another calcium based algae. With the color, it could be the start of Padina.