[Gibeon]

Ahhh... plumbing fun time!

On the acrylic and glass - you can use aquarium silicone to hold the baffles in place, the pressure is pretty much equalized. I just wouldn't make a tank out of acrylic and silicone.

If there are sections where the baffle has a pressure differential (return pump area I'm guessing) I would use thicker acrylic and brace it against the pressure by adding pieces at right angles to the baffle where it meets the glass on the low pressure side.