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.
Gotcha! TYVM! You have been very helpful! I have the API Nitrate kit. I should probably get a GH test kit as well as a Po4 kit.
Would the api po4 kit be enough? Should I buy a salifert po4 instead? I have immediate access to a API p04 kit whereas the salifert I will have to drive an hour away to get or order online.