I run my blues and daylights 8 hours a day on my 29g biocube frag tank. After daylights go out, I leave the blues on until I go to bed and then turn them back on in the morning for about 2 hours before I turn the daylights on. My frags are doing fine and growing great. Just be sure that when you ask or research before you buy, be sure you know where in the tank they will do the best. Low, mid, high. What flow they want as well. Lighting in the tank is only part of it, knowing a little more about each individual corals wants/needs is also really important. I have a 3 level frag stand in my tank with each level overhanging the next so that I can be sure I can put my frags in the location that will best work for each of them. Just something to think about to start off with the best chance for success possible.