To really get the coraline growing you are going to need to upgrade your lighting! I agree with Thechad you can easily go with VHO setup and have a great looking tank. Even cheaper if you are a DIY kind of person. You can buy the ballast and wire it up yourself. I think most of us recomend the PC fixture because they are a complete system enclosed with bulbs and fans and most of the time moon lighting. Usually these fixtures are professional looking with mounting legs. If you go with the VHO route you most likely will have to build a canopy for your tank to house the VHO endcaps and bulbs. In the long run it will be cheaper to go with VHO setup!
HTH......Just adding to what Chad said