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Re: Divider Glass/Middle Support

From: "Ken Guin" <kenguin at erols_com>

Raymond Yeo wrote:

>The question is ....i have this piece of glass glued right in the middle
of the top of the tank and it look like it's for the main support for
the front and rear walls. I don't really know how effective it is but
it's giving me alot of light loss when dust accumilates

>I would not remove the middle support. I had a 55g tank made some years ago
and the maker used a middle support. I thought it was ugly and removed it.
Several weeks later the aquarium cracked.

>Modern glass aquariums usually have a plastic rim around the top and bottom
with middle supports. Although these rims may look decorative,  I would
imagine they serve a very integral part in the overall strength of the

>If you could devise a way to put a "band" around the top perimeter of the
aquarium, you might be able to eliminate the middle support.  I once used a
stainless steel cable with swivel bolts (to tighten the cable) around the
top of an aquarium to give it more strength - it was an old aquarium that
had a tendency to "split a seam" occasionally.  It was not too esthetically
pleasing, but very effective.

As an engineer with some knowledge of structures, I don't think a band
would work unless you put a strut at the middle of each side of the band,
at right angles to both the band and the glass, with its length about a
quarter (or more if you don't like taking risks) of the length of the glass
side.  This is to make the tension in the band act inwards on to the glass.
Without this, the tension in the band will be simply contained within it
and run parallel to it and therefore parallel to the side of the tank, and
have no component pressing on to the glass, and therefore have no effect.
The band would work well to prevent the adhesive at the corners of the tank
giving way, but not to replace a cross-piece.  Also, a cross-piece is in
tension and therefore very strong.  It would be difficult to het the same
sideways foce even with a strut.  The longer the strut the greater the
sideways force.

If I have not made my explanation clear, think of you pulling a rope tight
and *straight*.  Can it produce any sideways force from it in its middle?
No, unless the rope is bent at an angle in its middle, (as if it bent round
a tree) which is what the strut would force it to do.

Try my Web Site at http://www.netcomuk.co.uk/~lachlan/timber.html which is
on the History and Construction of Medieval Timber-Framed Houses.