I am using 1000w light in a 5x6 room, light cycle is 12/12. I am using fox farm once a week. I dont think I am watering too much, I only water when soil is dry a couple inches in. older growth is dying, curling under, browning first spots then whole leafe top leave look ok but some stems are purple. the new stems are purple. plants are about 4 feet from light. PH is 6.5. see pics...Please help!!!