Stupid Question - Need Answer

[JackSpadesSI]

So I was about to set up my 30-gallon tank yesterday when something gave me pause. Does the bottom glass of an aquarium need to be directly supported? I'll explain...

My tank has an accompanying stand which was built for this aquarium. The stand is hollow (for storage) with cabinet doors on the front and holes for filtration tubes on the back. The top of the stand is open, as well. The way the tank is secured on the stand is by wood trim which locks the bottom lip the tank. The tank slides in from the back.

I'm quite confident that the tank is well secured on the stand. That's not the issue. My issue is that, because the aquarium isn't sitting on a flat table, the only thing between 300 lbs of water, rocks, and fish, and three feet of air below is a piece of 3/16" glass (assuming the bottom glass is the same thickness as the sides).

Does that sound safe to you???

 

[fort384]

I prefer to have the entire bottom supported.

 

[neilanh]

Most glass aquariums are designed and built to only be supported around the edges and wrapped in the lower trim which is all that would touch the stand anyway.

 

[JackSpadesSI]

Most glass aquariums are designed and built to only be supported around the edges and wrapped in the lower trim which is all that would touch the stand anyway.

That's what I was thinking. As the bottom glass isn't flush with the bottom lip, even if I were to place the tank on a table I still don't think that pane would be supported (directly, at least).

Maybe it just looks more daunting when I look through the (currently empty) bottom and see 3 ft of empty space. Besides the safety of the fish, which is obviously a concern, I will be keeping this tank in the same room as my expensive computer so the thought of a catastrophic spill in that room gives me cold sweats!

 

[fort384]

LoL I understand. I am not basing my post on any facts... I have always had a flat bottom supported entirely with my tanks, it I would just be freaked out like you to not have it setup in that manner.

 

[JackSpadesSI]

Can anyone else chime in to attempt to reassure me that a thin pane of glass can actually support ~300 lbs?

 

[Phlex]

take a look at this video..

YouTube - Tempered Glass Aquarium

 

[Homedog98]

Wow

 

[Mr. Limpet]

Can anyone else chime in to attempt to reassure me that a thin pane of glass can actually support ~300 lbs?

I can give you my rimmed 37g (raised bottom glass panel) setup as an example. My stand (a heavy duty cabinet) has raised 1x4 trim on either end which the tank ends rest on. In order to support the front and back panels of the tank I put 1x2 trim wood from end to end to fill this gap. The entire bottom area of the tank has no fill what so ever, it has been setup for over a year with no issues. Total est. weight of my DT is 350lbs.

IME/O, as long as the rimmed bottom of the tank is supported and level, you're going to be just fine.

Rimless tanks DO need full bottom support. The panel isn't designed to be self supporting.

 

[fort384]

LoL looks like good proof that you might be ok without having the entire bottom supported. Especially since the load was distributed over such a small area of the glass.

If the trim extends past the glass and it is not flush, having a board across the bottom won't change the way it is supported anyway.

 

[Phlex]

Thanks to your question it prompted me to do some research. Looks like as long as the glass is of good quality tempered glass, there isn't really a weight capacity that we could over fill for an aquarium. As long as nothing sharp is directly on the glass creating a pressure point, and the stand is level, the tank should be able to withstand any amount of weight we could put in it for normal aquairum use.. I've seen 300 gallon aquariums holding 7000lbs on a hollow wrought iron frame. So i think your fine.

 

[JackSpadesSI]

Perhaps I am being overly critical of that (albeit impressive) YouTube clip, but I'm still a little nervous (less so, though).

The video showed that was ~90 lbs of rocks - a far cry from ~300 lbs of water/gravel/rocks. Yes, he stood on a few rocks for an estimated 220 lbs, but who's to say if that would have held for 5 years.

My tank and stand are made by All Glass. The stand was made for that particular tank and they were bought together (18 years ago, according to the inspection date of 1993). The stand is as good as new, and nothing is visibly wrong with the tank. Am I good to go? Is All Glass a reputable company?

 

[fort384]

I agree, there is a difference between short term and long term loading, and material fatigue is a big concern. It is important to note though that he had all ~90lbs (and then 220+lbs) on a small area of the glass. Your load will be distributed somewhat equally over the entire bottom.

All Glass has been making aquariums for a long time. I would say they are reputable.

 

[Mr. Limpet]

Perhaps I am being overly critical of that (albeit impressive) YouTube clip, but I'm still a little nervous (less so, though).

The video showed that was ~90 lbs of rocks - a far cry from ~300 lbs of water/gravel/rocks. Yes, he stood on a few rocks for an estimated 220 lbs, but who's to say if that would have held for 5 years.

My tank and stand are made by All Glass. The stand was made for that particular tank and they were bought together (18 years ago, according to the inspection date of 1993). The stand is as good as new, and nothing is visibly wrong with the tank. Am I good to go? Is All Glass a reputable company?

That video, although interesting isn't a good example since all the weight is being put on a single (small) rock and not the entire bottom of the tank.

Tempered glass on its surface is very hard to brake, tap its edge and it'll explode. (I worked in a window mfg plant years ago driving fork lifts and trashing bad door panel glass was one of the fun jobs )

 

[JackSpadesSI]

It seems that All Glass is now part of Aqueon. I have no idea how they have changed their tank design in the last 18 years, but according to their website they do NOT use tempered bottom glass in their new 30-gallon tanks!

http://www.aqueonproducts.com/assets/011/19107.pdf

Is there any way to know if mine has tempered glass? If not, then that video doesn't really apply to my aquarium.

 

[Laurence]

To be safe I would put a sheet of 1/2 inch plywood under the tank, and a layer of styrofoam or felt on top the plywood to cushion the glass and relieve stress. Three-sixteenth of an inch of glass does not seem sufficient to support 300 pounds of water, unless the glass is laminated for strength.

 

[neilanh]

To be safe I would put a sheet of 1/2 inch plywood under the tank, and a layer of styrofoam or felt on top the plywood to cushion the glass and relieve stress. Three-sixteenth of an inch of glass does not seem sufficient to support 300 pounds of water, unless the glass is laminated for strength.

I'd warn against this without discussing it with the manufacturer first.

Again, remember that these aquariums are designed so that the bottom plate of glass is suspended by the lower trim. This was done on purpose.

Putting a flat surface and foam under there that makes contact to the glass can cause point loading to occur (similar to the video where all of the weight is point-loaded into the footprint of that smaller rock). Point loading something is the main way that glass breaks.

Now, I'm not saying it's not possible to put foam under there, but without talking to the manufacturer I wouldn't advise doing it freely.

 

[JackSpadesSI]

Well, the sides are 3/16". I'm merely assuming that's the bottom thickness, too.

 

[Mr. Limpet]

Well, the sides are 3/16". I'm merely assuming that's the bottom thickness, too.

Depending on tank size and shape, different thickness and types of glass can be used. On my 37g tall, there was a warning not to drill the back pane as it's tempered glass, but the side panes could be drilled as they're standard glass (non-tempered). I don't know about the bottom, but it's suspended a 1/4" above the bottom of the rim.

Now I figure that Topfin calculated the stress on the bottom panel to support a normal aquarium setup. If not they'd be out of business in no time repairing peoples ruined carpet, flooring, etc if it wasn't properly designed.

If I had a custom or home made tank, then I'd be worried. As long as the bottom rim is properly supported and the tank is level, I feel perfectly safe with it as it was designed.

 

[Kurt_Nelson]

Most tanks with frames are designed to be supported by the frame only. It will support the weight. You do NOT want to support the bottom panel with any foam, etc. Doing so will cause uneven support of the bottom panel and will risk breaking it.