Grey/black film on macro algae and sand

[Martini5788]

Starting a week and a half ago, I have this grey film that is taking over the sand and growing on my macro algae. What can I do about this? And what is it?

 

[lpsouth1978]

That looks like cyano bacteria. Physically remove what you can and check your water parameters with quality test kits. You can also increase your flow in the tank using power heads or wave maker pumps. Cyano is a sign that there is something wrong in your tank. Search the forums for "Cyano" and you should be able to find info on causes and treatment.

 

[CStrickland]

+1 cyano, sometimes it isn't red
See how in the second pic it's growing up under where the flow has pushed a little sand dune? That's what people mean when they talk about it liking low flow

 

[Martini5788]

Yeah that's what I thought too. What threw me off though is that it's grey. There is no red or brown in it at all

 

[Violator]

Can anyone tell me what this gray black formation is?

 

[j.falk]

This is EXACTLY what is happening in my tank right now! Good deal. Now I can get to work figuring out what is causing it.