Your tank sounds lager than mine but I just upgraded to the R2 5 LED kit from nanotuners, http://www.nanotuners.com/product_info.php?products_id=97 which is a small 4-5 inch tube with 5 LED lights in it and it looks amazing in my 29 gal biocube. They also have a larger kit which is the R2 10 LED kit, http://www.nanotuners.com/product_info.php?products_id=459 which looks lke it's just two of the smal tubes. Anyways, I can honestly say it's very bright, blue and vibrant in my tank and I'm happy with them.
this is my DIY moon light, its two LED night lights from wal-mart over a 10gal. you could probly do four over your 48" tank on a timer or get the senser ones like i did. they have blue or white.