glass tanks support: edges only??

GregS

AC Members
Feb 13, 2007
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I have heard the idea that glass tanks only need to be supported on the edges rather than the whole base, which seems counterintuitive since with a 4 foot tank that base is going to be holding up over 200kgs, held on by the 4 edges of silicon on the sides.:eek:

Could anyone offer their opinion on the need for support only at the edges, or if for larger tanks (ok 4 footers) whole of base support is required?:rolleyes:
cheers

Greg
 
If u look at the bottom of most tanks the plastic sits lower then the glass so the only thing that is supporting the tank are the plastic edges, not the glass on the bottom
 
the tank in question, which has not been filled yet, is a 'custom' size, just over 4 foot, by 18" by 18" high. It does not have plastic trim around the edges. If a solid base in thought to be necessary, i exepected to go with a foam 'underlay' to further spread the load, and accomodate the difference in height between the edges and the base (and trim if it had it).
Cheers

Greg
 
that idea accords with my own thinking. The stand for it has 3 braces accross the middle sections as well as one on each end. But still, all that water plus substrate makes me nervous about not supporting the base. I guess I wouldn't use a base if i heard a definitive answer and reason for NOT doing so.

Cheers

Greg
 
IME, acryllic tanks need the full support.

Glass is brittle, and unless you surface is completely level, you risk taking a change on causing stress. I use sheets of styrofoam under all my glass tanks, plastic frame or not.
 
Glass bottom tanks usually require the use of a foam underlayment. This can be seen for example at glasscages since their tanks are glass bottom: http://glasscages.com/?sAction=AqWarranty on a tank where there entire surface is flush with a full base any tiny imperfection will directly be stressing the glass, so foam will help minor imperfections. Most tanks you'll see at the lfs has plastic frames on them so when on a stand they are only supported around the perimeter. Also, most stands I've seen at an lfs similarly only supports the tank round the edges. In this case foam is sometimes not recommended, but not required at the least. So it basically depends on what type of tank you have. I've even seen 55g's supported just at the corners (corners were 4x4 posts, and the 2x8 that went around the perimeter was around the tank and not supporting it) I dont recommend this though.
 
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Hi Folks,

Just an update. I now have the 5 support beams (90x45 mm), then a full layer of 12mm ply, then a full layer of 12mm foam. By the way this tank does not have plastic trim, but I dont think that would have influenced my decision. My understanding is the plastic trim is mostly cosmetic.
And now comes the fun part - the scaping and stocking. I am not sure at this stage whether to swap over most of the scape and stock from my 3 footer, plus some additions of course, or whether do another new tank. Current water restrictions make me wonder about the wisdom of too many tanks ...

Cheers Greg
 
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