hi bro, my tank is about 5 months old, and it does have coraline algae esp in my sump. what i did is to make sure that my corals where doing well first,( at that time LPS) so i had to make sure my water perimeters were good, and after all my livestock where doing well,( low nutrient, good KH,CAL,MG ) Then i started to see coraline algae. so what i advise you to do is that you should first take care of your water perimeters, try not to add too much fishes and see that your corals are doing well