An algae outbreak means there is too much of "something" be it light, nitrates, phosphates, or some combination. It can be surprising how little extra it takes, too. Try doing a 50% water change in addition to your regular water change schedule, reducing your lighting by one or two hours, and feeding a little less.
Also, can you be a bit more specific about water parameters other than "perfect"? and what test kit are you using?
Someone stop me! Please! But... not just yet...
55 Gal Tropical FW
55 Gal Mixed Reef