I worry because I feel like the gravel might create some outward pressure of It's own, and combined with water the pressure may be too great. Also, gravel is pretty much the heaviest drainage layer there is, hydroballs or another type of similar drainage layer might be better, since the glass is thin. It probably won't matter if you're going to leave it in one place, though. The PVC false bottom might be better too. I've also seen posts about using plastic egg crate, but I don't know too much about the pros and cons of each type. One solution to the problem of water pressure might be to make sure you can siphon it before there is too much. A nice way to do that is to work on some gray PVC and run it vertically down to the drainage layer. You can use a knife, dremel(id you have it), and some sandpaper to make the gray pvc look like (ugly) wood. How good it looks depends on practice. Mine look...mediocre. I wish I wasn't poking holes in your build, but I'd hate for anything to go wrong. I really hope the drainage layer works in it.