I've got tons of thoughts. How do they get that big ship in that little bottle. Why is it always darkest before the storm. Why did..........whoops, oh ya, your question.
If your tank is new then algae is usually a given. Most people will tell you that they have had the same thing. Watch how much you feed, that can really add to your problems. Cut back on your light period for a while and that will help as well. Almost everyone goes through the same thing for a while.
Lighting can also add to the problem.