I've been reading about the Walstad method, and I think I get the basic idea: soil, a lot of fast growing plants like water sprite and hornwort, no filter. The fast growing plants absorb ammonia, nitrite, and nitrate and reduce the need for filters or water changes.
So why do you need soil for this? Why doesn't this method work with any substrate? I would assume that soil would only benefit rooted plants, but the ones people keep naming get nutrients from the water column, right?
So why do you need soil for this? Why doesn't this method work with any substrate? I would assume that soil would only benefit rooted plants, but the ones people keep naming get nutrients from the water column, right?