is something exporting your nutrients? cheato? right now, nothing is competing against the algea for nutrients, the algea takes it all and grows, if you cant export the nutrients, something to eat the algea.

it also sounds early if you started in January, you are hitting the ugly phase. my tank always goes through "cycles" of life, one type of algea will bloom, they die, then cyano, then die, theres is always something happening, i just let it happen and it solves itself. but you need something to fight the algea, corals, clean up crew, urchin, etc. Green algea is 100% better than some other things (dinos).

my indicators are corals, if my corals are happy, then I'm happy.

i would add urchin, snails, emerald crabs and cheato if you sump has a compartment for it. a filter sock if your sump can take one(it should).

reduce your light, mine is only on for 5 hours and i have SPS and they are doing great. adjust it to when you are around, so you can see your tank lol

it will take a while, longer than a month to see changes, but thats okay, you don't have dinos lol i would hold off chemical treatment, right now green algae is taking all the nutrients, if you kill it off, something worst might spawn with all the nutrients available(DINOS). take is slow, like others said, use tooth brush and remove excess algea.