ah ok, I misunderstood. In my thread you kept saying "rock", so I assumed you meant lava rock. I went back to the beginning of your journal and see the hydroton. My bad! Well, now you have me doing on this research on lava rock, and I'm thinking about trying it out anyway The thing I don't like about it is the sharp edges will cut roots... so that's what I'm afraid of.
It won't hurt the roots bro, a lot of folks use it..........combined with soil or by itself with hydro.