What is this Algae?

[xbrl001]

Tank has been running for about a year and now there is a very strange looking stuff growing on the rocks. It isn't growing on the glass at all. There are some pics below, its like a very light purple and is mostly growing in the "cave" in my tank but is now showing up in smaller amounts elsewhere. Any ideas? Doesn't look like diatoms or hair algae to me?

 

[twilliard]

It can be a bacteria

 

[rebekwl]

Possibly some type of sponge?

 

[cloak]

They look more like sponges to me as well.

 

[xbrl001]

If it is a bacteria, is there a chance that it could make the water toxic for fish? Are you aware of any parameters or factors that generally contribute to bacteria manifesting itself like this?

 

[xbrl001]

If it's a sponge, I guess that means that my water has excess nutrients?

 

[cloak]

Not necessarily. Sponges are just part of a reef tank one way or the other.

 

[rebekwl]

Not necessarily, they're pretty common and can be a sign of a healthy tank. I've always seen quite a few in my tanks