Hi, let me explain. First none of the online calculators accommodate my situation. Its a 60"L x 30"w x 20" h shallow tank. The builder did not make it all with 1/2". It is 1/2" bottom, 3/8" sides. Since I was not convinced of its integrity with 3/8". I did a 3" wide top and bottom eurobracing using 1/2" as well as a 10"w -1/2" center brace. It looks very solid altogether, and the water level is set to 17.5"h. I'm hoping for a safety factor of about 4 to tell my insurance. Any help? Thanks