Please verify what this is....

[islandcreation]

I have this 66 gallon tank running for 5 months now. Purple coraline algae looks great but for some reason I am beginning to see darker algae begin to grow on the rocks! I do have a sump with chaeto and other algaes, flow in the tank is over 1,000+ gph... What have I done wrong, or what can I do to prevent this. I see this happen far much worse at bigger pet shops like super pets. Here are the pics, please help.

 

[rescuediver19]

The pink stuff?

 

[islandcreation]

No... the dark dark brown areas.

 

[rescuediver19]

Im not sure what it is but have you tried to siphon it off? how "3D" is it (how far off the rock does it come?)

 

[islandcreation]

Its on the rock and I think its pre-coraline. I think my rocks are beginning to all turn into purple coraline. So far their about 1/3 covered.

 

[wettank]

What sort of clean up crew do you have.It looks like some sort of brown algea buts its hard to tell

 

[islandcreation]

I've got hermit both blue and scarlets and nassarius snails. I'm pretty sure its turning into purple coraline! Thanks

 

[Jennie]

It looks like it could be the beginning of a diatom bloom.

HTH