I am about to start setting up my vivarium which will have a 5" pool of water on the bottom for some fish. The land mass will be on a platform above the water line. I am going to use PVC for support, but I was wondering what garden stones would be safe (non toxic with no PH effect) to place in the water to use at the visible edges?

Also would be a better surface for underwater plants (moss) to grow on? Garden Rocks or Fiberglass Screening? In my setup I can either run the screen behind the garden stone or in front of the stone.

Thanks
Mark F