This will help----
Today Ryan is taking the new Orphek V4 Atlantik LED Light for its round of testing. The Orphek light is much different than other systems we have tested so far since it is made up of a panel of LEDs instead of clusters. Orphek is a leader when it comes to LED lighting for reef tanks and today we are
www.bulkreefsupply.com
I'm running two Icons on a 150g--- 60x24x24 and have them at 18" above the water line. I know once my Sps colonies get larger I'll have to add a few Led strips to get good coverage unless I keep all my acros in a 48x24 area.
If you're going full Sps then they will be good for 48x24x24 for sure. If it's a mixed reef or more LPS and softie dominated two lights is all you'll ever need.
Orphek recommends 15-18" I believe as they have plenty of power at that height.