How do I get rid of this brown algae?

Those are called Diatoms. If you increase your light you'll have less, but you'll have more green algae, so you need to keep your nitrates low, or zero. I cant see your pics link problem I guess. Adding live plants will help keep down nitrates, or if you just use an active charcoal filter you need to change the carbon once a week. You can actually reactivate your carbon by cooking it in the oven at about 200 degree Farenheit. All tanks get yucky over time, the pictures you see of beautiful tanks aren't run of the mill. A read an article that stated that most planted tank award winners they don't even add fish until right up to when they take the picture.