bulbs penetrate to a depth of 24" if I remember right. You are fine for just soft corals, but with you being towards the high end of the max depth penetration, you may want to place things in the upper 2/3 or 1/2 of the tank instead of on the bottom to achieve best color and growth from everything. I do however, recommend that you look and invest in a T5 HO
set-up in the range of 4-6 bulbs since later you may want to move into some of the higher light LPS
corals. Buying the better fixture now will save you some cash in the long run. Hope this helps.