My .02 worth. I have tried the Radium 20k DE, and the bulbs are very finicky. I also tried the Phoenix 14K DE, and both then tank looks better, and corals responding better to the Phoenix 14k vs the radium 20K. Phoenix is a very, very underrated bulb, and I think you will be hard pressed to find anyone who has used these bulbs to say anything negative about them. The radiums get all the wows, but I think there is a big difference between mogul radiums and DE radiums. That being said, the Pheonix bulb rocks, plain and simple. Its really closer to an 18K bulb although they market the bulb as 14k blue.