Photosynthesis is dependent on light in the blue spectrum. The eventual colors of animals may depend on a wider spectrum, but, they can't develop without photosynthesis from the blue light. This and Tim's answer are the long way of saying that blue light is imperative! If you use Coralife actinic 03, the manufacturer (reefers) say they last for 12 months. I believe I read a study on that in agreement. I can see the deterioration in other bulbs in 4 months with my eyes and the bulb ends are dark. The Coralife are not the same. They are not as cheap as the other bulbs either.