Re: Dry Land Tanks

["S. Hieber" <shieber at yahoo_com>]

Moon said:

> One thing about that set up. The center tank will have to be glued
> down or it 
> will float up in the center with a surprising amount of force. I
> tried it 
> once and silicone rubber wasn't strong enough to do the job.
> 
> Moon

Silicone is a low adhesion adhesive.  It works best is compression
joints rather than tension joist.  The typical aquarium would bust
apart (or slowly separate) if the rims weren't holding things together.

I had thought gravel and rocks would be enough to hold the tank down --
hadn't thought through any of the math for bouyancy.

Interestingly, if the moated tank *must* be afixed to the bottom of the
moat tank to hold it (the moated tank) down, this means the bottom
panel of the big tank (the moat tank) will receive an unusual stress --
pressure down around the outer areas and pressure upwards in the
center.  All of which reminds me, in a way, of Dick Feynman's sprinkler
puzzle.  I can imagine him posing this:  If the center tank normally
weighs 30 pounds but is then glued to the bottom of the big tank.  then
it is pulling upwards on the larger tank.  So is the larger tank 30
pounds heavier with the center tank glued to its bottom?

Scott H.

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