this. also, i don't see "black" algae. it looks more brown/red than anything indicating diatoms or dino's. considering the lack of coralline algae, i would assume the tank is new which would point towards diatoms, and or dino's/cyano(if your nutrients are 0).
what are your water parameters? what size tank? what kind of filtration/flow do you have? do you have fish? is the tank cycled? how old/new is the tank?