Macros: Nitrate, phosphate, potassium (plus calcium and magnesium if you're using RO water or your water is low in these nutrients)
Micros: Iron, boron, copper, zinc etc etc. Seachem Flourish has these nutrients already, so you just need macros.
You'll need to make sure all of these elements are readily available to plants by dosing multiple times per week, replacing what the plants take up.
If you don't want to DIY ferts, you can buy ready made ferts like the Seachem range. Seachem are pretty diluted and expensive. There are better preprepared solutions available.. someone else name these please, I'm in a rush.