ahhhhh no wonder they are so beautiful!

My 55g tank only has two 15w lights so no wonder my amazon swords do not do too well.
I have a box of Jungle Lab "tank buddies" Plant Care Fizz Tablets. I have been nervous about putting an chemicals into the discus tank and so havent used it yet. It says to add 1 tablet to each ten gal water so that would mean like 5.5 tabs a week! Im just not sure this is a good thing for my fish to do this. What is your opinion on this? Do you think I can use that much? Or maybe for two small amazon swords I can use less? And can you recommend a tank light that is not too expensive but would give me the right light for low-medium light plants?

for your help!
~ kate