Very nice. I love how the simple sand, rocks and a central plant mass layouts look. Has a very nice feeling of wasabi...err...wabi-sabi.
I see you've got some of the grout stuff in the silicone corners as well...any clues as to how to get at it or get it off? It seems like it's bonded with the silicone somehow and just refuses to come off. I've had diatoms grow on it but they come right off and that stuff remains.