Hi lee your post is a bit vague. Perhaps if you provided a few more details we could be more assistance. Usual details would be your tank current parameters such as SG, ph, alk , cal, trates, po4 levels and or what ever you happen to be testing for. Pictures often help.
That being said. After the initial nitrate cycle the "new tank syndrome" will be in full effect for a while. Many people will experience a few various algea blooms ( including diatoms which will be brown film like) possibly a bacterial bloom. It's pretty common and often corrects on it's own. Heavy bacterial blooms may require action on your part. Good luck