Algae issues please help

[S&A REEF]

67.5 gallon DT + 24 gallon frag tank + 20 gallon sump running gfo and carbon, 200 micron filter sock, bubble magus curve 7 protein skimmer. SPS dominate bare bottom tank with a lot of flow. Lighting is 4 x 39w T5 2x blue plus and 2x coral plus and an AI Hydra 26 running ab+.
Cal. 450
Alk. 8.2
Mag. 1500
Nitrate 5-8
Phosphate 0.05

 

[Spare time]

Dinos? Maybe try dosing phytoplankton or hooking up UV. Your Nitrante and phosphate don't seem that low thought some im not sure why you would have those unless you removed rocks or something lately