I have 4 24w T5 bulbs. 2 actinic and 2 10,000k. I was also thinking of changing out the 10,000k for 20,000k. My tank just looks white with a tiny hint of blue but the bright green and yellows of my zoos don't pop at all. You can clearly see the colors but it's not as bright. They look amazing in my moonlights though.