Note the feather like growth.
I am too new to make an assumption, but I agree with the advice of watching your CUC.
Whatever it is, don't freak out, the tank is new, and WILL eventually have a bloom. Just wait it out, and keep up on maintenence.
You are building an ecosystem, and if there is a huge monoculture, it will eventually kill itself. This is why you don't see rolling hills of blueberry bushes in the wild. They would eventually deplete all the required nutrients for that exact species and die off to a sustainable level.
Patience, and diligence.