Live and learn I guess. I didn't figure there would be enough pressure from the water to warrant using thicker glass on the base, but if I ever build another large tank like this I'll definitely take it into consideration. I did use aquarium grade silicone, and thankfully that wasn't the cause of the leak. I do wish I could refill it as a paludarium, but I'm still pretty happy with how it looks now. All of the plants are now emergent instead and doing just fine. We also just had our carpet restretched so the tank is back where it was intended to be. I'll post a couple of pics tomorrow.