you don't even need to overdrive them if you are housing any livestock(SPS or Clams). It's amazing. I have it over 2 of my 3 tanks right now, and the color is just unbeatable for the price. I run 2 48 inch actinics and 2 175 metal halides over my 125(relatively low lighting), and I couldn't be happier witht the T5's. I think I would go all t5's if I find a good deal on that setup.