Black film on sand???

[Pito]

I have notice this week a black film getting larger and larger over my sand. Does any one have a idea what this could be??

 

[username in use]

Sounds like a dark cyano. What are the tank parameters?

 

[Pito]

I just checked my parameters and all is fine. I had once a problem with that red slime and used that red slime remover and it worked. Should I try some that on this black slime??

 

[Sugar Magnolia]

Please list all parameters including phosphates. Are you using ro/di water? Running any GFO?

 

[Bluecheese]

Do you have pictures?
How thick is the film? Is it on top or crawling into your sand as well?