EI works very well if you have a lot of plant mass and a generous injection of CO2. It might still work if you scale it down, but you have some ferts in your substrate, and the plants you list are not extremely fast growers, so...
Me, I am curious myself, so I used some (few) test kits for a while, until I knew what was going on in my tanks, and how much nutrients I needed to add.
Thanks again. So here are some readings on my tap water:
Po4 (api test kit) 0.5ppm
KH = 40-50 (tetra strip)
GH = 150
Nitrate (api) 0
Hopefully that gives you what you need tyvm (or me)!