Soil or hydro? 400 watt bulb you should keep light as close to plants as you can get . what are your temps in your room? i read 12 inches. if the temps are kept cool. put you hand under your light if it burns your hand then raise it.
but i would keep around 12 inches from top of your plants. i cant tell what nutes. i dont know what your using. you have to go to the store to get nutes. right?. those guys know it all ask them. take it easy sorry no one else helped.
for the yellow leaves you have to make sure your ph is perfect. in the water and soil.