I can't tell you about an acrylic tank, D, but for a glass tank, if there is plastic trim on the bottom edges of the tank glass, then no foam required. My Glass Cages 100 gallon glass cube is rimless with no plastic trim on the bottom, and Glass Cages says to put styro between the tank and the stand. Which I did when you helped me carry the thing to my basement 4 years ago or so!