Lighting question.

[tim the toolman]

I am currently running a 14 bulb 6' T5 system which runs 8 daylight bulbs 4 actinics and 2 Fiji purple. In the past when I do a bulb change I would swap out all 14 bulbs. Now my question is, do I have to change the blues and purples or does changing the whites only do the trick. I always assumed that the other colors were just to accent the coloration of the tank life.
Also I am open to suggestions regarding the mixture of bulb colors I am using. I run 4 10000K and 4 14000 K bulbs. Trying to grow out sps and other various corals. Thanks to any and all input.