. Heavens. I've read everything I can on lights. My mind has a tendency to shut down when they're too many numbers in front of me. However I do have 2 of the the Home Depot plant/aquarium light bulbs 15watts each. But I still cant understand it. I know I have lowlight I just want to know if I get LED would that be any brighter? I have a 40gal 36" long 21" high planted tank.