Kingbrite 240W

Doctorgreen thumb summed it up pretty good. Ill just add that i think one of the 240w will plenty of light until mature in veg. Also 30" is plenty far enough, if your plant node spaceing is stretching to much then just turn your light up a bit

LED grow lights, those are the hardest lights for which to estimate an ideal hanging height. There is just so much variance in the output of different LED brands. They are also deceptively strong, especially the red and blue mixed lights (i.e. not the all white LEDs). The light looks dim and it doesn’t feel very hot, but it can scorch the plants nonetheless. For this reason, you want to keep a close watch over your garden, whenever you start using a new light, until you get a feel for the ideal grow light height above plants. Most manufacturers provide the recommended hanging height for their lights. If that is the case for your light, start with your light hanging at the distance they recommend. Watch your plants closely and back the lights off if their are any signs of bleaching (i.e. the leaves begin turning white). If the plants are fine, move it a bit closer until you reach the point where they begin to bleach the leaves. Then back them off again and you have your ideal height (for flowering; for vegging, back it off 6 to 18 inches more). I would start a seedling @ 30 inches and see how she reacts. you say you have a dimmer you can always dim it down more or move it up. Gl