it wont make your tank look blue at all. 50/50's come out this kind of off white color. how long has your light setup been running? why is it being changed? is there something you're striving for or was there a problem?
colors in the 14-20k range are your bluer colors...and the corallife bulbs arent actually blue...they're more purple. but when combined with whites i think they look spectacular.
hope that sheds some light