Aquarium sand

[Mosmoove]

can anyone tell me what's this brown stuff is. Its not on glass but in the sand.

 

[Sgooosh]

can anyone tell me what's this brown stuff is. Its not on glass but in the sand.

Diatoms probably, the gravel is white so you can see it.
why i dont relaly like white substrated lol!!
should be fine

 

[Mosmoove]

Diatoms probably, the gravel is white so you can see it.
why i dont relaly like white substrated lol!!
should be fine

Thanks