Well, I love the concept, but the rock looks like a guy just piled it up. I would want something that looks more natural. Maybe put a break in there somewhere to make 2 rock towers..something that makes it looks like a natural environment.
As for the hair algae....shut the lights off. Why do you need lights on if you don't have photosynthetic creatures in there yet? During the initial cycle, there are a lot of nutrients in the water. nutrients plus light equals algae. Limit the light.