Depends. People have used envirotex epoxy for direct in tank applications as well as on starboard, and people have used pvc glue on roughed starboard. What are you gluing to what?
I was thinking of glueing sugar fine sand to sheets of acrylic. I have both on hand. I was also tenkering with the idea of glueing crushed coral to acrylic to use on the back of my 220
