I'm doing the same to a 150 gal tank I picked up, the previous owner broke the top brace so I couldn't pas the price up. I called the tank manufacture (miracles) to confirm the dimensions required, I was amazed how helpful they were. If you bought the tank new this will void your warranty. every thing that I have read has stated the same thickness as the tank front panel as a min and 2-3" wide depending on the length of the tank.