The brown algae is likely brown diatonomous algae, which shows on the glass as brown powdery stuff.
It requires silicate, which is present in most new tanks in good quantity. However, as you use your protein skimmer, I assume you have one, it will remove algae particles containing silicate, and in this way over time, reduce the silicate level in your tank. Because of this, the brown diatonomous algae will gradually dissapear.
Not quite so easy with the green algae though, which does not require silicate, but does need phosphate. Phosphate can be removed by the skimmer in much the same way as silicate, but the problem is you add more phosphate every time you feed. So green algae may take a bit more beating, you need to have a means in place to remove at least as much phosphate from the tank, as what you are putting in with food etc.