I have a pair of the 55W GE 9325K bulbs (which are obviously danged close to 10kK bulbs) in a 4ft strip light. They put out a good white light, and the plants are slurping it up. I changed from 6500K bulbs, and know what you mean about the yellowish cast - though they look nice in my 20gal unplanted tank for the livebearing fishes (Pineapple Swords look good, but the Endler's Livebearers look a bit bland compared to the 9325s). Granted, I also more than doubled the watts per gallon, too, so that has more to do with the plants' happiness than the color, but the plants and fish look great. The Tetras (Black Neons, Lemons, and Glowlights) really pop with the 9325s. The reds of the Alternanthera and Ludwigia are especially nice with the whiter bulbs.