I've actually drille dholes in the rocks and slid them down over the top of the PVC pipes. On the couple of pieces I've tried, it works pretty well. I imagine I will have some rocks that will break, so I will use them for filling holes and stacking on top later. I am taking photos as I go to post later, if it all works!. I have drilled holes in the pipe, and the ends are open, to make sure I get some water flow in there. I have not heard or did not know about raising the pods though, I'll have to research that.