You really need to strike a balance between lights, CO2
, and fertilizers. Else, you may get growth deficiencies, algae, or both.
Dry salts (or fertilizers) are often recommended because of their effectiveness, ease of use, and cost (low). There are two primary types: Estimative Index (EI) and Perpetual Preservation System (PPS). More info on these can be found at Green Leaf Aquatics and NilocG. Basically, you mix the fertilizers with water and dose daily as instructed. It is designed to provide more fertilizers than the plants need so there is no deficiency. I like PPS-Pro (from GLA).
There are several liquid based fertilizers; I would recommend a combination of Seachem Flourish Comprehensive and API Leaf Zone. I used that for about a year before switching to PPS-Pro.
I remember this tank. You started this at the beginning of the year. Some sick, sick MC growth you got there! Very impressive.