matt clark;2945657; said:i have bin working it out and the tank comes to arount 7000g. what sort of acrylic thickness do you think shoud be looking at
If you are actually consulting structural engineers, as your sketch indicates, they should address that question based on tank height and the actial dimensions of the windows. It will be very thick, like 3 to 6 inches depending on whether you split it into several panes, or have one large pane.
looking forward to more pix....