Help me fix my glass mistake......

[masharp1126]

Building a 450g plywood tank. Interior dims are approx. 72"x48"x30". The viewing window is about 66"x26". So I'll have 2"+ support all around. My screwup was I ended up ordering a piece of 1/2" starphire glass for it, thinking it would work. I didn't take into account the front-to-back depth of tank and the extra pressure it would create. I now realize that I should have at least 3/4" or 1". Any suggestions would be appreciated. A couple of ideas I've come up with include:

1. Buying a 2nd piece, either 1/4" or 3/8" and having a glass shop laminate them together for me. Good idea or bad? Haven't priced the laminating, so it might not make sense price-wise.

2. I can't afford to totally scrap this piece and buy a solid sheet of 3/4" or 1" glass. So, if acrylic is cheaper, I could go with that instead of glass. Then just save this piece for something in the future. If I do go acyrlic, how thick should it be?

Help! Looking for any other suggestions you might have.

 

[rdbrown]

I think you are okay. Pressure really goes up in height, not much with depth as it is gravity that creates the pressure.

 

[Conner]

Well. GARF.org doesn't recommend 48" wide plywood tanks, so it won't say what thickness glass there. But for an all-glass tank of those dimensions, 1/2" glass is fine, so I would think it would be fine for a plywood tank as well. If you're really worried about it, you could decrease the size of the window with more wood, and just use the same piece of glass. That would create more support around all 4 sides of the glass, and decrease the pressure on the exposed glass.

 

[sk8zeroatskewl]

i would go with a middle support frame in the middle of the glass if you want to be a hundred percent safe on this might not look as clean but will still be more safe

 

[Bderick67]

The over all width of the tank does not add pressure only the height does. One foot wide or four foot wide, same pressure on the glass.

i would go with a middle support frame in the middle of the glass if you want to be a hundred percent safe on this might not look as clean but will still be more safe

You do mean at the top of the glass don't you? Either way not sure how this would make it "100% safe"

 

[Conner]

You do mean at the top of the glass don't you? Either way not sure how this would make it "100% safe"

I think he means if he puts a vertical support beam in the center of the glass, it would essentially split it into two window panes, and decrease the pressure, or at least reduce bowing. Not sure how it works to put a mean in the center of a piece of glass though.

 

[the_deeb]

I think you should be fine with what you have. For extra peace of mind you add an additional 3-4" wide strip of glass along the top edge as a eurobrace. Much cheaper than buying and laminating on a new piece.

 

[greengiant]

height is really all that matter and unsupported width. if you have bracing across the top of the tank as well then yhe glass can only bow to as far as the next brace is.