If all the water is reverse osmosis then are you reconstituting it with calcium, magnesium and carbonate? No expert at RO use, might be more stuff needed as well. And if you aren't using phosphate, add that in too. With your high powered set up you might need to add more than the bottles of fertilizers suggest too.
No sure what your light is but you might consider using a shorter lighting period and or using fewer bulbs. You have loads of CO2, perhaps the light is over whelming it.
You might put a ripple on the water surface to aid in oxygen exchange for the fish. Is the CO2 and fertilizer well distributed in the tank with lots of water movement? 3 times the tank volume used to be suggested but now 10 times is suggested. When I move my powerhead to blow across algae ridden areas it seems to help get rid of it. Algae grows fine in high current areas too but sometimes it settles in a low flow area and changing that condition helps get rid of it.