Thanks for the updates!
my Acrylic tank has a clear back that I was planning on either painting or fastening a blue sheet of acrylic on the back. Now that I see what the spray foam looks like, I think I'm going that route.
It's hard to tell from your pictures and I know that you do have a dark back wall, but will the foam be able to cover the entire back adequately? Or do I still need a dark background to start with?
Thanks for your time!