Thanks Lump. It's too late now... the substrate has been spread across a part of the yard that is landscaped precisely to have nothing grow on it. You know, like where you see wood-chip mulch spread in around the base of trees sometimes. It's over the natural soil, and under the mulch.
Hope it doesn't hurt the trees. But from what you've said, that may not happen. Thanks.
Steve - 33g reef and a 180g planted in need of a re-scape.