Aeroflo Leaf problems

I am using an aeroflo2 20 with rockwool cubes and hydroton. I use RO water with an initial ppm of 6.9. I am currently using Tiger Bloom and Beastie bloomz with a ph around 5.8. Plants are abotu to enter 5 week of flowering and i am having a lot of rustly looking spots on the leaves. I thought it was nute burn so i flushed the system and started fresh with ppm at 600 after adding nute. Air temp is about 77.8 and water temp is 70. I have a tek light 8 bulb 434 watts running 11 hours a day. RH is 44% and i have 3 fans blowing circulation around the room. I raised the light about 5 inches from the plant due to heat issues.