A pic would help, there are many different kinds of algae, some good for the rank some not.
Sometimes removing all the rocks and scrubbing stuff off can create a mini cycle which is not a good thing, but that again, depends on the species of algae.
For many African cichlids a lot of the right kind of algae is a good thing, and part of their natural biotope, and they eat it.
If it is cyanobacteria they won't touch it, and is problematic.
The pic below is cyanobacteria (slime algae)

Cyanobacteria isn't necessarily effected by amount or hours of light, it can be enabled by overfeeding. I used a probiotic to help control it (rid-X).
And maybe since your tank is new, if what you have is slime algae. A probiotic would provide the right kind of bacteria to compete with it. There is a long sticky, about probiotic use.
And by the way, it is not a food, like a human thinks of probiotic, but it is a bacterial additive to the tank water.