Supplies:
1 can of "great stuff" wide gap filler: its this foam that comes from a can
1 bag of sanded tile grout
1 bag of sand
Basically I sprayed the foam where I wanted it, waited for it to dry, and then grouted it. While the grout was still wet, I covered it in sand. Here is the finished product. It is a ten gallon. If you need any additional info, feel free to ask.
Edit: I did 3 sides of the tank. Saves room to put the tanks sideways. lol
