I built a 380G tank using this method about 15 years ago. I used 1/4" acrylic on the sides, back and bottom and used 1/2" for the viewing window. The tank measured 96"x30"x30". I used silicone along all of the seams. The tank lasted for about 3 years before I noticed a hole had developed on the bottom of the tank where I had attempted to install a drain and then did a poor patching job. I have heard that silicone works poorly with acrylics but I didnt have any problems with this build or on the sumps I have built since then using acrylics and silicone.