Just bought a 300 gallon tank. Filled it up doesn't seem to be any leaking but looks like it is bowing a bit in the middle...it measures 60 1/2 cm on the corners and 61 1/2 cm in the middle, so about a 1cm bow. Is this ok? How do I fix it if not? the glass is 1 and a half cm thick. The tank dimensions are 8ftx2ftx2.5ft. It has no support in the middle, I was going to make my own out of glass but didn't know if it would even do anything, so I just filled it up slow to leak test it in my garage. No leaks just bowing...Thanks for any help or encouragement you can provide!!