Why does coralline only grow on glass

[Treenk]

Any idea why I get so much growth on the glass but nothing grows on the rocks?

 

[Mr Cypher]

that is unique as hell lol mine grows everywhere power heads rocks glass crazy

 

[homer1475]

Yup mine grows pretty much everywhere too.

I have plating coralline right where a PH blows on a rock. Looks similar to a plating monti, but it's purple. My urchins love it! I wish they didn't because it's pretty cool looking.

 

[Koh23]

Did anything grows on rock, some algae, stuff?

For me, order was, brown phase, green phase and now finaly purple phase takes place....

How old is tank/rock?

 

[Treenk]

The weird thing is, the frag wrack was from my old tank and it was covered in coralline, now it's not. It's making it difficult to out compete the cyano, and gha. I keep having to treat for them biweekly one then the other.

 

[Treenk]

This tank is around 6 months old, but the rock was from my bigger tank which was around 3 years old. There was no new tank growth like diatoms etc.

 

[Treenk]

The lower right rock was covered in the purple you see on the glass when I put it in, and now even it just looks like a normal rock.

 

[G Santana]

I have similar issues, my tank is 16 months old and started with dry rock. At close to the year mark I started to get coraline on the power heads and glass bottom and overflow but little on the rocks.
I just took it as long as I have it growing somewhere all is good lol