I was looking at your past posts and wasn't able to determine exactly what size tank you have your frags in and if they are alone or with fish. Was this tank treated when you had ick?
Water quality issues tend to be the reason for most algae issues. Even if your parameters are normal I highly recommend doing 2 10-20% W/C per week until the issue goes away and highly recommend keeping the light on as you normally would as it will keep from stressing your frags. You can use a turkey baster or a feeding syringe to blow the algae off the area and I highly recommend you do this every day until it is gone. Just make sure you vacuum as much as possible of the blown off algae from the frags when doing a water change.
Where are you getting your water from? Is it RO/Distilled?
I had cyano for about a week appear on one of my rocks and a couple W/C's while doing what I said above fixed the issue.
Best wishes,