This is my first grow. Blue Dream at 21 days. Soil is FoxFarm ocean.Watering cautiously. Every 2 to 3 days to give soil chance to dry. Fiber 5 gallon pot drains well. No extra nutes given. Was all good until day 19. My best guess is lack of iron? PH was 6.5 to 7, now 6.5. Appreciate your...