FOOTNOTE: I went by to visit with a previous customer while I was in Napa - her build survived the quake, all the structures stayed intact and no rock slides! I love Emaco...
The acrylic gives me the basic dimensions as well as a solid building surface (I always cast the base rocks with a fglat bottom to assure a stable build.
No issues that I am aware of - when you first add to a tank it leaches enough silicates to give a small diatom bloom, but that is about all. It stays strong and stable...