I just went out and bought that bulb last night! I set up a 2.5gallon for my fire red's. The bulb it came with was so brown it made the tank look nasty. This bulb from what I've herd is the perfect spectrum for plants (6500k). Its also super bright compared to the stock one! It is a nice crisp white light no brown or yellow tinge. No joke though I've herd that bulb by zoo med is the best you can get for those 15watt sockets. Also that bulb should be plenty of light for 5 gallons!
"One generation plants the tree, the next generation gets the shade"