Lighting for a 55g

[upaquariest]

I have a standard dimension 55g, stocked with a discus and an angel and several other fish I am planning on adding 3 more discus and a couple angels. The lighting right now is an old 48" GE AquaRays fresh and saltwater 40w flourescent, I am planning on replacing the bulb and possibly adding a blue spectrum bulb to help bring out the color in the discus, I would like to stay with flourescent because I am doing this tank on a small budget what bulb or bulbs would work well with this set up