Judging from the pic, the lighting youre using doesnt look all that bad, the rock and the sand look very white, not too bad in my opinion. As Jim said, Im experimenting with the 400W XM bulb, so far its not too bad as far as color goes with 110W of 10K PC supplimenttion, the lamp was "virgin" when installed and I anticipate it to turn a more crisp white after a week or so burn in period. As far as intensity goes, this lamp is a freakin power house! Very similar to my 250W Iwasaki, just a different color. Its taking me a little time to get used to the change, but I think its gonna be just perfect!
Jim