The Kelvin ratings for CFs are related to the ratio of redish spectrum (700nm) to bluish spectrum(400nm). the Ratio is balanced at about 6000 Kelvin. I have had 10k Kelvin bulbs in two of the slots in my hood, Do I need 10k bulbs?or is it a waste? I have a ballast that controls six 96 watt bulbs,two are actinic (cause the cool looking) and the others range from 6700 K to 10k K. I think it's about time to make some switches for new bulbs, because they have been in for a while. Should I replace them all at once or a couple at a time? 5000 K bulbs or 10000 K bulbs. The Actinics can stay for now...