Chris;

Get the hamilton/Ushio 10ks. They're the only higher kelvin bulb i know of that come close to the PPFD of the iwaskis, which I assume is what you're running. Supposedly, there's a newer iwasaki "R" bulb which is not as yellow as the old ones. You could try those, too. Man, I've heard lots of bad things from folks running bluer bulbs for any length of time. John Moffett used to complain about 'em all the time. I've got an old magizine around that did a pretty thorough analysis of 250W MH bulbs for PPFD and CCT, if you want to have a look at it. But basically what it said was that DE HQI's were the highest in PPFD, then iwasakis, then Ushios, and everything else was way lower. If I remember, the CCT for the DE was about 11K, the ushios 10k, and the new iwasakis around 7k.

On my next tank, I'm definitely going with DE HQI. I'll just start saving now.

HTH
Matt