I had it happen when I went away on vacation. What I was told, and worked great for me is this:
1) Cut feeding down to about every 3 days, just until it goes away.
2) Feed less per feeding
3) Maybe increase water changes till it goes away.(make sure you use RO water)
4) The most important... cut down lighting. I went from 8-10 hours a day down to 4 hours or less. Over a period of about 1 month and a half I worked it back up to 8. I kept it at 4 hours until the algea disappeared however.