I have a few plants (water sprite, pothos,onion plants, corkscrews,amazon sword, anacharis)in my 150G sump. I have a shop lite with two four feet (38W) bulbs T-5. Half of my plants are doing ok while the others wilted away slowly. I keep my temp in the mid 70s with 30% weekly WC. My LFS guy said i need to add supplement so he sold me a bottle of Nitrogen for $8. I also noticed they have other supplement for sale. Do i need any of this ? Thanks