[t2000kw]

We don't have your water, of course, but we used a simple arrangement with topsoil and some black sandblasting medium (instead of aquarium gravel) on the top. We planted everything and let it settle. I think we used a DE filter to clear the water initially to save some time, but it isn't necessary. No fertilizers. It worked out well. You may be making this too complicated, and if something goes sideways, you will have too many variables to sort out. You may not have a lot invested in the aquatic life, but I'd hate to lose even a single fish. Consider starting with the Walstad basics in the book.

 

[t2000kw]

What do you think is too complicated, exactly? Maybe we think of different parts of my planned setup.

As Diana stated earlier:
"You've made this a very complicated project. It's as if you don't trust or understand natural processes. In my book, it's a layer of potting soil covered with a layer of sand/gravel and lots of plants.
Maybe this will work for you, but if it doesn't, Heaven only knows how you will be able to sort out any problems."

Simply put, you've added more variables to the mix than a regular natural planted tank would have. It's no longer a "Walstad" tank. If something goes amiss, it will be very difficult to sort out what happened, if it was something you did when deviating from the book, etc. Sand, gravel, lots of plants and nothing else keeps it simple, it works, and there's nothing else in the mix to add unnecessary complexity to the setup, which makes it easy to figure out what happened if something goes wrong. Why try to reinvent (by adding more things to the mix) what already works for thousands of people?