I agree with the sandwich idea for the brace and the weld on is a must. Silicone will not work. I'd be more afraid of the bowing in the back. That 2 pieces of 1/4" acrylic is crazy!
Yup I can't believe the back was built this way. Didn't see that when I bought it. Front doesn't look even remotely that bowed. This stinks. I need water in this thing asap.
Tank was $500. Stand came with it but will get replaced.
Funny thing is this tank may end up being the sump for the real monster tank. Lol.
Might throw up a pic of that one tomorrow. Just unloaded it. 3 guys 2 hours. 30 feet.
If it were me I would sandwich the top brace with plexi and glue and run a few dowels/stainless screws thru it for insurance. And for the bowing I would make a structure for the tank to set in. Like the plastic bracing around glass tanks, execpt i would make to on the top and bottom and then have a few braces run from top to bottom on the back side to push the tank flat again and keep it there.------------------------------------------------------------------------I hope you understand what i am trying to say, it is easy to picture in my mind but not so easy to say.----------Several people on here have made wooden top bracing for tanks that surrounds the perimeter. Hope fully they will chime in.
After cleaning the broken joint, the area on the top of fracture and the area on the bottom. Apply weld on to the fractured area, and using 2 3' clamps (Hardware store usually about 15 bucks each) clamp the tank from the front to the back on both sides of the fracture.
Then using 2x 1/2" thick scraps that are larger than the fracture I would weld on the 2 pieces (One on top and one underneath) and then again clamp them using 2 or 3 clamps.
This fixes the fracture but doesn't fix the poorly designed back. For that I think your only option is to back it up against a wall and then brace the tank somehow on the top and bottom to prevent the tank from moving away from the wall and allowing that back to bow again/more. I think something like movers straps which are anchored into the wall studs would be the easiest just have to make sure you get big ass lag bolts that won't tear out of the studs when the tanks full of water.
You may need to use a few hair dryers to heat the back up to get it flat again with out fracturing it so you can brace it to the wall while it's flat.