I think the reason they look dark to us is because LED companies like ours want to use only beneficial areas of the spectrum so as not to waste the precious LED energy. Coral respond best to spectrum in areas where the light does not appear bright to us even though a PAR meter would suggest differently. Our eyes are very sensitive to light in the yellow/green spectrum and there is much of that spectrum present in metal halides along with the beneficial spectrum. There are a few (including our lights) that do a pretty good job creating the metal halide shimmer look. Here is one example.I have switched and switched back. I like kessils because they look like MH, but LEDs make the tank look so dark. I love how bright the tank looks withMH. To get that with LEDs would surly pump out huge PAR numbers with lots of fixtures and likely toast coral. Radions sounded nice but also made the tank look dark and the flickery shimmer was annoying as i have lots of surface agitation.