The roots self prune or just stop growing at the top of the res. Why? I don't know. But they do not grow down into the res. I'm guessing that the Air Gap between the soil & the water causes it. The perforated platform for instance is 6" high. The drain hole in your bucket is 4" high. So you can only add 4" of water / feed. That creates a 2" Air Gap between the Soil & the water.But I'm still confused as to how this should work as air gap.. with a perforated top that gives access to the soil? how do you prevent roots from growing straight into the water where you have to end up putting in an airstone to prevent stagnation and root rot and now you're in dwc territory..
Or how about that autopot base, that indeed keeps feeding with a valve but what if I place two root pouches on that with the bottom 2 inch filled with hydropebbles and perlite and then soil so that provides an oxygen rich wicking environment?