I am not using 10K either. I have a hard time locating a distributor that carry my odd size 21" t-5 bulbs. Therefore, I'm using el cheapo 4200kelvin t-5 lights. I cannot complain since it's only $5.99 a bulb.Hao;3808526; said:thanks man idk my 150's light is white but not 10k and umm my 100 is sorta bluish white but more white