glass thickness

[cary Henderson]

Maybe someone can help here..
making a 8'x2'x20" lxwxh plywood tank....
how thick glass should i get for the front..
all the plans i find don't give a glass thickness..
figure 3/8 but this is alot of water...
any feedback would be great...

[Richy]

http://saltaquarium.about.com/cs/aquariumdiy/l/blcustomtank.htm

This may help. According to the chart I would use 16mm.

Richy...

[sphelps]

10mm (3/8") glass would be more than enough, you could even get away with 6mm as long as it was tempered and good top bracing was used. The only two things you need to worry about with glass thickness is pressure and deflection:
Pressure is all related to height, a 50 gallon tank 20" tall has the same pressure as a 400 gallon tank 20" tall, length and width have nothing to do with pressure (Pressure= density*gravity*height).
Deflection will depend on the length of one side, if a side is only 2 feet in length the deflection or bow will be minimal, however with an 8 foot side the deflection will be much greater. Bracing is the best way to deal with deflection. A euro brace is the strongest brace when it comes to deflection, and a few center braces may be required depending on glass thickness chosen.

Personally I may go with the 6mm tempered in a Starphire, just for clarity. But you may sleep better at night with a 10mm. Just don't go overkill with 12mm, my biggest pet peeve is the glass thickness overkill, it does nothing but add weight and reduce clarity.

Good luck with your project.

[sphelps]

Also not sure if this helps, but here's a plywood tank I designed for a customer:
http://i11.photobucket.com/albums/a174/sphelps/plywood.jpg

Dimensions were 96x30x32 I believe and 1/2" glass would have been used.

[sphelps]

http://saltaquarium.about.com/cs/aquariumdiy/l/blcustomtank.htm

This may help. According to the chart I would use 16mm.

Richy...

You read that wrong, according to that chart 9mm or 12mm could be used at 21" of height. However since the tank is only 20" tall it's likely the water level will be closer to 18" so 6mm or 9mm could be used.

I've never heard of 9mm glass though. Also remember tempered glass is 7 times stronger than standard float.