I am running 2 6500k bulbs, one Giesemann Aqua Flora and one UVL Red Sun. My fish and plant's colors really POP. I also have a 3000k but found it too yellow if I used in place of one of the 6500k. By the way, the 6500k bulbs that I have are by odyssea...they seem bright, but I don't know how they compare to other brands. The UVL red sun is an awesome bulb. It's super red so you would have to have other colors in the mix for sure. Who makes your 6500k bulbs?