I'm going to give you a few recommendations here as you may have meant 96 inches instead of 69. Regardless of what people say the length of the aquarium must be considered as well as the depth (vertical).
96x48x36 (safety factor of 3.8 unsupported/rimless)
Side thickness: .93" or 23.66mm
Reverse Calculation for 3/4" glass: 2.5 safety factor
IMO 3/4" glass should be safe enough in a supported plywood tank with top bracing
Fill to 24" 3.8 SF
Side thickness: .51" or 12.88mm
Reverse Calculation for 3/8" glass at 24" water depth: 2.1 SF
IMO 2.1 is low on the safety factor but can be used properly braced.
If on the other hand you were doing a 69 inch tank....
At 36" using .625 or 5/8" glass would give you a safety factor of 2.0, again that is low and I don't personally like it. However you may be able to find 18mm glass and that would give you 2.54 SF. the recommendations for 24" are the same as above.
Hopefully now you can make an educated decision. GL
http://www.monsterfishkeepers.com/f...rmuds-Glass-and-Acrylic-Calculator-(it-lives)