On my 38g, I have a Marineland Double Bright 36"-48". This light was very disapointing from the beginning, giving a yellowish light. So I bought a couple of supplimental strips, a couple moonlight strips, and added 2 10w royal blue chips. Now I really like the color. The supplimental strips are 2 Tru Lumen 10" strips with 2x 12,000K & 2x 453 blue, and the moonlights are 2 Tru Lumen Lunar lights w/3 453 blue. The 10w led chips, drivers, and heatsinks are cheap from China, but have been functioning great since September 2012. Under just the 2 10w chips, all my corals, which is mostly zoas, palys, and mushrooms really flouresce.
Prior to the leds, I had a Odyssea 4 bulb T5 fixture, with the stock bulbs. That really did nothing for the corals.