If you have 80 PAR at the substrate you need to dose more than "lean" EI doses of fertilizers. That is enough light that you should be trying to make sure the plants growth is not restricted by nutrients shortages. The point of the EI dosing method is to keep a small surplus of all of the nutrients available to the plants at all times, so only the light is restricting their growth rates.
Substrates leach whatever nutrients they contain into the water, so adding small dishes of different substrates doesn't show the effect of having any of those substrates in the whole tank. Also, the substrate has only a small effect on the plants growth unless there is too little of some of the nutrients in the water. And, one more thing, many plants have big root systems, for various reasons, so putting those plants in small dishes in the tank will either force the roots to climb over the edge of the dish into the main substrate, or it will restrict the growth rate of those plants.
This will be a fun project, but don't expect the results to mean a lot.