Just my $0.02 but I when I was ready to start my upgrade to a 72x20x20 tank Lighting was the thing holding me up. I read up on various different fixtures for the 6' I needed to cover and when it came down to it I wanted something with the ability to grow all kinds of corals.
But at the same time not costing me a fortune to upkeep (both electrically and bulb replacement etc).
After searching for a good 4 months I found a thread on another community about the Evergrow D120 units. Now at first I was thinking it seemed to good to be a true, a LED unit for 180$ that could grow coral? That was until I saw people who have been using the 1st generation ones (just blue and white leds) over there tanks for over a year. The Corals looked AMAZING they reported noticeable growth within the first few months and even better coloring than previously when under MH and T5's.
I am a firm believer that the hobby doesn't have to cost you thousands to get results you want. Especially when it comes to LED lighting. LED's are cheap to make and the upkeep is almost none. Plus with the ability to dim the LED's you can get the effect you want without using 4 different colored bulbs over your tank. I would say tho with the ability to dim LED's and setup the colour ratio it could also be a problem if the corals are not getting enough of one colour. Enough rope to choke yourself as they say.
I would look into the Evergrow Units be it the D120 series or the more expensive IT series both are great fixtures at a great price. But this is just my opinion and im sure someone will hate the fact that im promoting cheap LED units. Do your own research and check out all the options for your needs.
I purchased mine from Nick at reefsupplycanada and I have to say his customer service is amazing.
http://www.reefsupplycanada.com/evergrow-led-lighting/