Changing your bulb to one of a different spectrum will not necessarily make any difference in your tank. The actual brightness will not change. The fixture in your hood will accept only bulbs of a certain wattage, so you will be unable to increase wattage without retrofitting (gutting and replacing) the light fixture, adding another fixture to what you have, or changing it altogether.
It is certainly worth trying a different spectrum, shooting for 6500 to 10,000 Kelvin bulbs, but the plants won't respond dramatically. I hope I am understanding your post correctly, but let me know if I am not.