I have one plant that is directly in hydroton and doing pretty well. I also one that i germinated in pH adjusted rockwool, sprouted 3 inches, and 1" root out of the bottom in less than a week. Placed one layer of hydroton in the pot, then the cube, and then the sides and top of the rockwool. If you looked at mine you couldnt tell that its in RW. I like the retaining props of the cube, and I believe it could allow a buffer when the res level drops a little too far.