pressure on glass question (210 Gallon tank)

[GetITCdot]

I am in the beginning stages of building a 4 1/2 Foot (54 inches) long, 2 1/2 feet tall (30 inches) and 2 1/2 feet wide tank. the back, sides, and base will be wood while the front will be saphire glass. According to my math (wich if it is not right please god tell me) this tank will hold 210.4 gallons (im rounding down to 210 Gal) wich at 8lbs a gallon would be 1680lbs. However is all the weight pushing out? Or is the 1680 devided by the 4 sides it will be pushing out against? Acording to my glass thickness guide i will need 12mm thick glass wich is around 1/2 inch glass. But while calling some glass places they told me half inch glass will NOT support that kind of weight. What do i do?[SIZE=-2]
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[AquariumNerd]

The glass guide is most likely expecting you to still use stress bars on the top of the tank. These are a must have, the tank will be really week without these, also I would use at least two cross bars. Make the main stress bars run along the top front and back of the tank. Use thick glass and give them a front to back size of around three inches. You should give the cross bars a width of around four inches, do this and your tank should be fine.

 

[KLee79]

30in tall and 1/2 inch glass will be fine. but like aquariumnerd said, use bracing...

 

[Jgray152]

But while calling some glass places they told me half inch glass will NOT support that kind of weight. What do i do?

The glass sides will have different pressures on them at different depths. 1680lbs is the weight one bottom glass.

For every 2.31 ft, you have 1 PSI. so at the bottom of the glass sides you will have 1.08 PSI roughly.

Depth(ft) / 2.31 = PSI
2.5 / 2.31 = 1.08 PSI

30" x 54" = 1620 sq/in
1620 * 1.08 = 1749 lbs of force on the bottom glass.

if you look at this thread below you will find a lot of good information I posted on ehow to calculate hydrostatic pressures.
http://www.monsterfishkeepers.com/forums/showthread.php?t=228880&highlight=2.31