I am getting a new tank that is 6ft long 2ft wide 38 inches deep. Will a led light be strong enough for the depth of the tank or should I go with the mh?
The right LEDs will be fine, but they won't be cheap. You'd be looking at Radions, AI Vegas, or Kessil a350's. You'd need three, possibly four of any of those fixtures for coverage
If the tank really is 38 inches deep, its going to be pretty spendy either way, it'll have to be a fixture using at least 3 watt Crees with optics, so most of the generic LED fixtures can get crossed off the list