Black film algae?

[Saumann7]

ive noticed this gray film like stuff in my sandbed, it is slowly spreading and I’m not sure what it is and I haven’t found anything online. Any help is appreciated! I can post different pictures if need be

 

[nautical_nathaniel]

It could be some sort of cyano but is most likely being caused by a nutrient issue. What are your water parameters like?

 

[Saumann7]

It could be some sort of cyano but is most likely being caused by a nutrient issue. What are your water parameters like?

That’s the weird part, nitrate <5 nitrite 0 ammonia 0 and I added chaeto about a week ago to try to combat it and so far it hasn’t been working

 

[Roy 9121]

Looks like some kind of bacteria, where's @Humblefish?