tank safety?

[sophie]

The school where I work has a tank with goldfish in the reception area
which has always been looked after by one of the teachers (successfully
and well, I think); however he left at the end of last term and I have
been designated term-time-goldfish-looker-after on the grounds that I
have had fish since february and haven't killed any yet... I'm pretty
sure I can look after the fish but I'm a little worried about the tank.
It's about 3 1/2 foot long and is stood on a fairly solid cabinet,
however the long sides overhang the edges by about an inch each. There's
no board underneath only polystyrene. Is this safe? To me it seems like
a lot of pressure to exert along one line of the base as the polystyrene
isn't offering any support at all, but I have been assured by the guy
who was looking after them before that it's fine. Is this one of those
counter-intuitive bits of engineering, or am I right and should I put a
board underneath?

many thanks for any help,
--
sophie

[Billy]

"sophie" > wrote in
message ...
|
| who was looking after them before that it's fine. Is this one of
those
| counter-intuitive bits of engineering, or am I right and should I
put a
| board underneath?


By all means, a tank should have solid support all the way around.
Putting a board underneath will be good, but getting a stand that
provides the proper support is the best option. The tank is currently
poorly supported, and one of these days,
term-time-goldfish-looker-after is going to be demoted to
water-mopper-upper-and-dead-fishie-picker-upper.

billy


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[sophie]

In message >, Billy
> writes
>
>"sophie" > wrote in
>message ...
>|
>| who was looking after them before that it's fine. Is this one of
>those
>| counter-intuitive bits of engineering, or am I right and should I
>put a
>| board underneath?
>
>
>By all means, a tank should have solid support all the way around.
>Putting a board underneath will be good, but getting a stand that
>provides the proper support is the best option. The tank is currently
>poorly supported, and one of these days,
>term-time-goldfish-looker-after is going to be demoted to
>water-mopper-upper-and-dead-fishie-picker-upper.

sadly I don't hold the purse-strings, but I do have a large piece of
exterior ply.
is this exploding-tank scenario, or leaking tank scenario? It seems to
me more likely to cause the kind of stress that would result in the
former (at least without the board underneath), but at least if it
started leaking the school would probably buy a new stand (and tank,
come to think of it.) Their view at the moment is "oh, it's been fine
for years, you're worrying about nothing" - which is understandable, I
suppose.
--
sophie

[Billy]

"sophie" > wrote in
message ...


| sadly I don't hold the purse-strings, but I do have a large piece
of
| exterior ply.
| is this exploding-tank scenario, or leaking tank scenario? It seems
to
| me more likely to cause the kind of stress that would result in the
| former (at least without the board underneath), but at least if it
| started leaking the school would probably buy a new stand (and
tank,
| come to think of it.) Their view at the moment is "oh, it's been
fine
| for years, you're worrying about nothing" - which is
understandable, I
| suppose.
| --

The older that tank gets, the weaker the joints are going to get.
There is pressure in places and in directions that weren't designed
to withstand pressure. If you can't get proper support for it, by all
means, put in the plywood, it's much better than betting on "nothing
yet, why worry." <g>


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[NetMax]

"sophie" > wrote in message
...
>
> The school where I work has a tank with goldfish in the reception area
> which has always been looked after by one of the teachers (successfully
> and well, I think); however he left at the end of last term and I have
> been designated term-time-goldfish-looker-after on the grounds that I
> have had fish since february and haven't killed any yet... I'm pretty
> sure I can look after the fish but I'm a little worried about the tank.
> It's about 3 1/2 foot long and is stood on a fairly solid cabinet,
> however the long sides overhang the edges by about an inch each.
There's
> no board underneath only polystyrene. Is this safe? To me it seems like
> a lot of pressure to exert along one line of the base as the
polystyrene
> isn't offering any support at all, but I have been assured by the guy
> who was looking after them before that it's fine. Is this one of those
> counter-intuitive bits of engineering, or am I right and should I put a
> board underneath?
>
> many thanks for any help,
> --
> sophie

I've had many tanks (10 to 20g) which were installed sideways in their
metal stand (so the ends & middle were in the air). I've never had any
problems. You might be inviting more trouble by messing with it than
leaving it alone ;~).
--
www.NetMax.tk

[Billy]

"NetMax" > wrote in message
. ..
| "sophie" > wrote in
message
| ...
| >
| > The school where I work has a tank with goldfish in the reception
area
| > which has always been looked after by one of the teachers
(successfully
| > and well, I think); however he left at the end of last term and I
have
|
| I've had many tanks (10 to 20g) which were installed sideways in
their
| metal stand (so the ends & middle were in the air). I've never had
any
| problems. You might be inviting more trouble by messing with it
than
| leaving it alone ;~).
| --

Aye, a tank that small isn't too much to worry about. How much do you
think a 3.5 foot tank weighs, though? :)

billy


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[Geezer From The Freezer]

Billy wrote:
>
>
> Aye, a tank that small isn't too much to worry about. How much do you
> think a 3.5 foot tank weighs, though? :)
>
> billy

Depends how wide and deep it is.

[sophie]

In message >, NetMax
> writes
>"sophie" > wrote in message
...
>>
>> The school where I work has a tank with goldfish in the reception area
>> which has always been looked after by one of the teachers (successfully
>> and well, I think); however he left at the end of last term and I have
>> been designated term-time-goldfish-looker-after on the grounds that I
>> have had fish since february and haven't killed any yet... I'm pretty
>> sure I can look after the fish but I'm a little worried about the tank.
>> It's about 3 1/2 foot long and is stood on a fairly solid cabinet,
>> however the long sides overhang the edges by about an inch each.
>There's
>> no board underneath only polystyrene. Is this safe? To me it seems like
>> a lot of pressure to exert along one line of the base as the
>polystyrene
>> isn't offering any support at all, but I have been assured by the guy
>> who was looking after them before that it's fine. Is this one of those
>> counter-intuitive bits of engineering, or am I right and should I put a
>> board underneath?
>>
>> many thanks for any help,
>> --
>> sophie
>
>I've had many tanks (10 to 20g) which were installed sideways in their
>metal stand (so the ends & middle were in the air). I've never had any
>problems. You might be inviting more trouble by messing with it than
>leaving it alone ;~).

it would certainly be a Task Of Large-ish Proportions. It's not so much
the lack of support that was worrying me as the lack of any real spread
for that amount of downwards force (I know the polystyrene takes some of
it but not all) along one line in the glass. On the other hand I'm not
sure how much extra spread a board would give.
Your answer is easier (but this tank is pushing 50 gallons, I think; I'm
only guessing at the dimensions so far); Billy's makes me think the
responsible thing to do would be to put the board underneath.
gah.
I need someone to tell me what to do.

--
sophie

[Ali Day]

"sophie" > wrote in message
...
> In message >, NetMax
> > writes
> >"sophie" > wrote in message
> ...
> >>
> >> The school where I work has a tank with goldfish in the reception area
> >> which has always been looked after by one of the teachers (successfully
> >> and well, I think); however he left at the end of last term and I have
> >> been designated term-time-goldfish-looker-after on the grounds that I
> >> have had fish since february and haven't killed any yet... I'm pretty
> >> sure I can look after the fish but I'm a little worried about the tank.
> >> It's about 3 1/2 foot long and is stood on a fairly solid cabinet,
> >> however the long sides overhang the edges by about an inch each.
> >There's
> >> no board underneath only polystyrene. Is this safe? To me it seems like
> >> a lot of pressure to exert along one line of the base as the
> >polystyrene
> >> isn't offering any support at all, but I have been assured by the guy
> >> who was looking after them before that it's fine. Is this one of those
> >> counter-intuitive bits of engineering, or am I right and should I put a
> >> board underneath?
> >>
> >> many thanks for any help,
> >> --
> >> sophie
> >
> >I've had many tanks (10 to 20g) which were installed sideways in their
> >metal stand (so the ends & middle were in the air). I've never had any
> >problems. You might be inviting more trouble by messing with it than
> >leaving it alone ;~).
>
> it would certainly be a Task Of Large-ish Proportions. It's not so much
> the lack of support that was worrying me as the lack of any real spread
> for that amount of downwards force (I know the polystyrene takes some of
> it but not all) along one line in the glass. On the other hand I'm not
> sure how much extra spread a board would give.
> Your answer is easier (but this tank is pushing 50 gallons, I think; I'm
> only guessing at the dimensions so far); Billy's makes me think the
> responsible thing to do would be to put the board underneath.
> gah.
> I need someone to tell me what to do.

I stayed out of it as I'm not a fish tank builder, but I have to say it
sounds suspect, BUT the fact the tank has been in use for a while suggest to
me that it might be better not to touch. If you could but a couple of
photo's on the web somewhere, taken from a low perspective, that might help
those in the real know to answer your question.

Cheers

A

[Dick]

On Thu, 26 Aug 2004 15:11:50 -0700, "Billy"
> wrote:

>
>"sophie" > wrote in
>message ...
>|
>| who was looking after them before that it's fine. Is this one of
>those
>| counter-intuitive bits of engineering, or am I right and should I
>put a
>| board underneath?
>
>
>By all means, a tank should have solid support all the way around.
>Putting a board underneath will be good, but getting a stand that
>provides the proper support is the best option. The tank is currently
>poorly supported, and one of these days,
>term-time-goldfish-looker-after is going to be demoted to
>water-mopper-upper-and-dead-fishie-picker-upper.
>
>billy
>
>
>---
>Outgoing mail is certified Virus Free.
>Checked by AVG anti-virus system (http://www.grisoft.com).
>Version: 6.0.744 / Virus Database: 496 - Release Date: 8/24/2004
>
Tanks don't put weight on the bottom glass, only the sides. The trim
puts a fraction of an inch/cm between the base and the glass, so the
weight is supported by the trim. I have seen lots of wrought iron
stands with no center support. I have one 10 gallon tank that is
slightly longer than the cabinet it sits on. The cabinet edge is
slightly higher than the top, so once more the tank is only supported
by the trim. Its been that way for over a year with no problem.
Having said that, if concern is going to worry you, I would improve on
the base just for peace of mind.

dick

[sophie]

In message >, Dick
> writes
>On Thu, 26 Aug 2004 15:11:50 -0700, "Billy"
> wrote:
>
>>
>>"sophie" > wrote in
>>message ...
>>|
>>| who was looking after them before that it's fine. Is this one of
>>those
>>| counter-intuitive bits of engineering, or am I right and should I
>>put a
>>| board underneath?
>>
>>
>>By all means, a tank should have solid support all the way around.
>>Putting a board underneath will be good, but getting a stand that
>>provides the proper support is the best option. The tank is currently
>>poorly supported, and one of these days,
>>term-time-goldfish-looker-after is going to be demoted to
>>water-mopper-upper-and-dead-fishie-picker-upper.
>>
>>billy
>>
>>
>>---
>>Outgoing mail is certified Virus Free.
>>Checked by AVG anti-virus system (http://www.grisoft.com).
>>Version: 6.0.744 / Virus Database: 496 - Release Date: 8/24/2004
>>
>Tanks don't put weight on the bottom glass, only the sides. The trim
>puts a fraction of an inch/cm between the base and the glass, so the
>weight is supported by the trim. I have seen lots of wrought iron
>stands with no center support. I have one 10 gallon tank that is
>slightly longer than the cabinet it sits on. The cabinet edge is
>slightly higher than the top, so once more the tank is only supported
>by the trim. Its been that way for over a year with no problem.
>Having said that, if concern is going to worry you, I would improve on
>the base just for peace of mind.

it's the fact that the long edges have no support that worries me. I'm
not an engineer but your point raises the issue that a fractional bow
might alter the outwards stresses along the vertical seams so that there
is more force applied at then top not the bottom. And I think this tank
is about five times as big as yours...

I think what I really need is an engineering group!

many thanks for your input, Dick, it's appreciated (as is everyone
else's)
--
sophie

[SDB]

Hi Sophie, I have a Master's degree in structural engineering, so I can
make a (somewhat) informed analysis of the situation. (I have the degree,
but I work as a technical writer in the software industry -- I decided not
to persue an engineering career).

The polystyrene only serves to level the tank in case the cabinet or floor
is a bit un-level, so your aquarium is supported only on the short ends.
From what I've read on the web, and from what I can see in the stands that
i've seen advertised, aquariums should be supported at all four corners.
That the long sides of your tank are unsupported is probably not a problem,
but that the corners themselves are overhanging the edge is probably not too
good.

Your setup is probably causing a lot of stress at the joints of your tank
(i.e. the glue-stuff that holds the panes of glass together at the corners).
All of the upward force from the supports is being exerted on the edges of
the end panes only. Forces applied to the end panes from the supports are
upward-pointing, and the other panes have downward-pointing forces applied
to them from the water. The glue-stuff at the corners is the only thing
keeping the end panes and the side panes from slipping in opposite
directions.

The glue-stuff is flexible, and you'd notice that the joints are starting to
fail before they actually did fail. However, glass is extremely brittle, and
any slipping of the corner joints would cause the bottom pane of glass to
bend and crack -- and because of the brittle nature of the glass it would be
a sudden failure.

That the tank has been set up for a while without noticeable deformations
occuring is not an indication that everything is ok. If the tank fails, it
will probably be quick and without much warning, because of the brittleness
of the glass. The catastrophe may occur when the aquarium is accidentally
bumped, or the water sloshes from, say, an earthquake.

You may want to consider supporting the tank at all four corners. Maybe if
the end panels were sitting on some 2x4's that were lain across the existing
cabinet, then that would be enough. But I'm no expert, so you should
probably confirm this with somebody who knows more about aquarium stands.

cheers
scott

"sophie" > wrote in message
...
>
> The school where I work has a tank with goldfish in the reception area
> which has always been looked after by one of the teachers (successfully
> and well, I think); however he left at the end of last term and I have
> been designated term-time-goldfish-looker-after on the grounds that I
> have had fish since february and haven't killed any yet... I'm pretty
> sure I can look after the fish but I'm a little worried about the tank.
> It's about 3 1/2 foot long and is stood on a fairly solid cabinet,
> however the long sides overhang the edges by about an inch each. There's
> no board underneath only polystyrene. Is this safe? To me it seems like
> a lot of pressure to exert along one line of the base as the polystyrene
> isn't offering any support at all, but I have been assured by the guy
> who was looking after them before that it's fine. Is this one of those
> counter-intuitive bits of engineering, or am I right and should I put a
> board underneath?
>
> many thanks for any help,
> --
> sophie

[sophie]

In message >, SDB
> writes
>Hi Sophie, I have a Master's degree in structural engineering, so I can
>make a (somewhat) informed analysis of the situation. (I have the degree,
>but I work as a technical writer in the software industry -- I decided not
>to persue an engineering career).

Scott,

thank you very much for this and thank you also for troubling to send it
via email, it's very much appreciated.

I was worried about stresses in a vague half-formed (and fairly
ill-informed) kind of way; it's been a while since I did any serious
maths/mechanics and you've put it all into sensible context. I did
actually contact a man who makes stands (the lfs who are very nice
people did it for me, in fact) and he said that if there was overhang
this was not a problem _as long as there was a board beneath the tank_;
I'm still uneasy about it, although I imagine he should know what he is
talking about. so my plan at the moment is: board under tank, with two
by fours as uprights (actually I think it is more likely to be one by
threes, given that the overhang is only an inch) bracing the corners
(wedged in and held there by the downward force/weight of the tank). The
board is heavy-duty exterior ply. I'm pretty sure this covers all
problems;' I'm certainly much happier about it now.

And we don't have serious earthquakes here, but a hundred-odd under
elevens do a very good impression sometimes! (I'm only part-time, so I
usually get to go home without a serious headache...)

thank you again,

--
sophie