400w hps should be no closer than 6" from top of plant to light. I prefer 8". For the nutrients I would use any of the FoxFarm Products or GH (General Hydroponics) brands for nutrients. You definently have enough light and airflow. Make sure temps in your grow tent stay around 77 no higher than 84 or they will retartd growth.

Post pics when you can. I would love to give you more advice.:hippy:

GoodLuck:,:thumbsup: