6" is a good distance for T5 lighting. Veg or Flower either one. BUT....you should always double your light in flower. Example: you have a 48--4' 8 bulb assembly. You veg using 4 center bulbs . Use all 8 bulbs for flower. Alternate spectrums---full spectrum. Gives more influence to those certain characteristics you are looking for. Tighter. Frostier. Oilier. Gardener talent prevails here. Blue-red-blue-red-etc......