I personally don't mind algae in my tanks. All three of my tanks have green algae covering the back walls, rocks, ornaments, and plants.
I prefer a more "natural" look to my tanks. I have enough fish and snails to keep the algae under control.
I did have a major outbreak of some kind of brown algea a while back in my 10 gallon tank. It occured when I removed the plants from the tank and transplanted them to my 20 gallon. I don't know why it happened. I eventually had to totally start the tank over from scratch after throwing away the substrate and bleaching the tank and filters.