Coralline or something sinister

[scotts8826]

Is this coralline algae battling with some green algae or is it something more sinister?

 

[Fish Styx]

Sadly, not corraline. That is Cyano or red slime algae, which is a misnomer, because it is actually bacteria. It is caused by flow, or lack there of and nutrient levels. Maintain WC schedule and nutrient export and it will generally resolve.

 

[Lavey29]

the easy way to tell is if it blows or brushes off easily. Then you know it it not coralline.

 

[scotts8826]

Thanks, Fish Styx. I'll commence a counter offensive!