I didn't use it either. I had it on a table. I just pluged the overflow with proper plumbing. It has one drilled hole in the back to use as an inlet if needed. Bottom is double layered. It is plexiglass.
20x20x8 Advanced Acrylics. Black bottom and back. Buffable scratch on left side as you face it. PM for my number for pictures. Posting picts here doesn't go well for me.