Professional's answers on bottom glass and frame questions

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The Zigman

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Oct 5, 2007
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Anything that is tempered needs to be annealed before it can be machined..
Steel, or glass..

all cutting, drilling, and shaping is done to glass before it is tempered.
 

CWO4GUNNER

USN/USCG 1974-2004 Weps
Original poster
Found out a couple more valuable pieces of official info in consideration of bottom cap method.
(1) the surfaces of the other 4 panels that will be resting on top the bottom glass must be finished flat without and high points or a crack will occur on filling (a small pit OK) and the 4 side panels must be even (1/32) most especially the ends cannot be higher then the side panels with respect to the bottom panel platform. This most especially important for some one like me who is replacing going from a free floating bottom to a capped bottom. For my situation looks flat but obviously wont know for sure until I set the new glass on top.
(2) Metal framing like I was considering angle steel support has to have the correct amount of silicon filler play and stand off from the glass noticeably more then plastic. This because steel and glass expand at very different rates and if not enough expansion material is available between the glass and steel, the steel frame will crack the tank during fill up or any temperature chnages.
There goes my great idea to weld a nice tight support bracket for the bottom, whew!
(3) Here is some good info I found on pro's/ con's tempered bottoms from the Federation of New Zealand Aquatic Society:
"Toughened glass is considerably stronger than standard glass. It cannot however be cut. If toughened glass is to be used it must first be cut to size, have its edges finished and then be send away for toughening. The thermal resistance properties of glass are also improved by toughening. Standard 6mm glass will rupture if plunged into water at 21°C if the temperature of the glass is more than 55°C hotter or colder. Toughened glass will rupture at approximately 250°C difference. Toughened glass also has a tensile strength greater than 5 times that of standard glass. Standard glass has a very important advantage when used on aquariums. It tends to fail in a non-spectacular manner, - typically a vertical or diagonal crack. Toughened glass however will fail completely, much like the old style car windscreen (100% shattering)."

(4) Also got confirmation that a flat full cabinet base with a layer of poly styrene make a difference allowing the bottom glass normally required to be thicker then the sides, allowed to be the same thickness as the sides.
"The thickness of the bottom glass is covered by a set of specific calculations (thicker), but does not cover an aquarium which has a bottom glass that is well supported from below the aquarium in an even uniform manner. The surface must be very level. On very large aquariums this can be difficult to achieve and self-leveling filler may be needed between the polystyrene and the base. This should be applied just prior to fitting the aquarium to the base so that the aquarium's weight levels out imperfections. Significant time must be allowed for the filler to fully cure before the aquarium is filled. If the bottom glass is only to be supported by all four edges then use the special set of calculations. The same thickness glass can be used on a uniformly supported bottom as well and this will significantly improve the safety factor. If the aquarium is to be supported from below in a uniform distributed manor, then the same thickness glass that is used for the largest side panel may be used. To do so requires the supporting base to support part of the load so therefore it must be VERY strong."
For me this is very important because my bottom glass was the same thickness as the sides and it sat on a perimeter cabinet which may be a contributing factor as to why it failed. So now I have to decide if my bottom glass should be .6 inches instead of .5 or just commit to a flat full base with the polystyrene cushion. Now I'm really worried about my 60 tank sitting on the fiber board stand, I just tried sticking a butter know between the tank and stand and the knife slips right in under the middle but the ends are tight.
 

RodInCALIFORNIA

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this is all way above my pay grade to understand LOL good luck with this project Gunner!
 

Sploke

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Fact. aquarium manufactures recommend stand be made of solid wood with flat strong supported surfaces to support the entire bottom glass as most new decorative framing is only 1/32 inch thick on the bottom. Perimeter support is not recommended.
This point also varies by manufacturer. I bought a Perfecto tank and stand combo, 55gal. I was looking under the stand the other day, the tank is actually held up by the ends. There is no support under the long sides of the tank, just two 12" lips in the stand that the tank sits on. And this is a stand designed/made by the same company that makes the tank.
 

Hebily

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Tempered is a lot stronger, it will not chip or crack. As stated, if it takes enough abuse, it will crumble. It will completely shatter, into thousands of little pebble like peices (that are NOT sharp). Standard glass can also shatter. It will crack or chip first. If it is strained enough, it will shatter, and the pieces will be sharp. This shatter point is lower than the shatter point of tempered glass. The only advantage of non tempered glass is that it can be cut.

Like any material, Glass (tempered or not) can take a certain amount of strain per area. It is cheaper to use this to your advantage. It is more reliable to not. A solid supporting surface will provide better reliability in that it 'backs up' the strength of the glass.
 

CWO4GUNNER

USN/USCG 1974-2004 Weps
Original poster
Tempered is a lot stronger, it will not chip or crack. As stated, if it takes enough abuse, it will crumble. It will completely shatter, into thousands of little pebble like peices (that are NOT sharp). Standard glass can also shatter. It will crack or chip first. If it is strained enough, it will shatter, and the pieces will be sharp. This shatter point is lower than the shatter point of tempered glass. The only advantage of non tempered glass is that it can be cut.

Like any material, Glass (tempered or not) can take a certain amount of strain per area. It is cheaper to use this to your advantage. It is more reliable to not. A solid supporting surface will provide better reliability in that it 'backs up' the strength of the glass.
Yup your right, the reliability factor goes up from like 1.8 to 3.6.
Well that's it I guess, I got butterflies but Im going to order the glass bottom today for a cap over fit if exactly 72X24 measures 3 times. While down their Ill find out the difference in cost between .5 inch what I have and .6 inch or the next thickest increment cost which doubles the reliability as well. But after having my car side window disappear when I leaned on it with my elbow is enough to give me the willies about tempered, also I would like time to evacuate the fish and control the water damage.
 

Hebily

My Tank \/
Mar 15, 2009
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Yes, the violence with which tempered glass can shatter is rather impressive.

My lab jumped out the drivers car window once. It was cracked about 1" open before he got to it. That took many hours of cleaning.
 

Rbishop

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Until I see it in writing from each manufacturer..this is just opinion to me...
 

Narwhal72

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My long awaited questions has been answered by professional factory aquarium builders.

Fact. the decorative trim on the aquarium has no benefit whatsoever in strength or structure but invented purely as a manufacturing aid to hold the panels in place during the gluing process. It is the silicone that does all the supporting between the panels not the decorative or assembling plastic framing. If you took it off it would make absolutely no difference other then to hold new panels in place for the gluing process.

Fact. Added bracing comes in the form of the center top glass strap where aquariums are longer then 48 inches and hold more then 100 gallons. The alternative is Euro bracing.

Fact. The bottom glass in manufacturing is never tempered unless special ordered due to its catastrophic failure nature (explodes when fails). Non-tempered is used because when it fails it cracks and the leak is usually a controlled spill.

Fact. The cutoff between using the "capped method" of bottom glass placement (all side panels sit on perimeter of of bottom glass) or "free floating method" (bottom glass is recessed inside and even with all 4 vertical panels) is when 1 inch glass is used.
Because of the sheer weight of 1" or larger glass vertical panels and the amounts of water they designed to hold would be too much weight to be sitting on top of the perimeter of the bottom glass using the "capped method", the "free floating method" is use instead which is a more difficult assembly process but no more stronger then the "capped method" in so far as bonding strength is concerned.

Fact. aquarium manufactures recommend stand be made of solid wood with flat strong supported surfaces to support the entire bottom glass as most new decorative framing is only 1/32 inch thick on the bottom. Perimeter support is not recommended.

*Incidentally, please do not construed this posting as any kind of slam on opinions we have all given including myself and which have help greatly in perusing the whole answer. These particular and crucial questions I sought out from the factory so that they would help us all have a solid foundation as to WHY these method are used and preferred by manufacturers.
I saw this thread and felt I had to reply. There is some correct information and some incorrect.
1. Frames do not provide structural support. Yes and No. Frames made from an extrusion that are miter cut and then glued together before being siliconed onto the glass do not do anything to keep the tank from coming apart. The silicone side seams are stronger than the glue used to hold the frame together at the corners. BUT....injection molded seams that are made of all one piece as is commonly used in Aqueon and Perfecto tanks 220/210 and smaller does offer structural support as the unibody construction is stronger than the silicone seams. Both types of frame are helpful in tank construction but the former is more for aesthetics and one other reason which I will get into later.
2. Center glass straps add support. This is true. So does the center brace in an injection molded plastic frame.
3. Bottom glass is never tempered. This couldn't be more wrong. Bottom glass is often tempered and is an increasingly common feature of aquariums. Tempering glass increases strength tremendously and allows the tank bottom to be made from a thinner material than nontempered glass which saves cost. Untempered glass is used in some tanks where the added weight is seen as a quality factor. In the U.S. heavier tanks are often considered higher quality. Side glass is rarely if ever tempered as most panel failures are the result of edge faults or damage. Aquarium frames protect the bottom glass from edge damage but do not protect the sides. It's better to have a tank chip than shatter.
4. Capped bottoms are made on tanks up to 1". yes and no again. I have never heard the term capped bottom before so I can't say that's an industry standard. We don't even have a name but we just call it a regular bottom. The name for the other style is called a floating bottom because the bottom is floating within the side panels. This style of aquarium is the standard in Europe and Asia with brands such as Elos and ADA making this style exclusively. It is much more appealing aesthetically in a rimless tank configuration but is much harder to construct. In this style tank the bottom needs to be supported evenly by a solid surface which is also the style of cabinetry used in Europe and asia. They make them in all sizes from 10 to 200 gallons. In the U.S. we use framed tanks which use the standard bottom. A 1" thick side wall would be an extremely large custom tank. 210/220 tanks made by Aqueon and Perfecto are only 1/2" thick side walls.
5. Aquarium manufacturers recommend stands made of solid wood because the frames are only 1/32" thick. Not true. Although there is nothing wrong with a solid top stand, aquarium frames in the U.S. generally support the bottom glass 1/4 to 1/2" off the bottom of the frame. Even a miter cut frame is this tall and is actually providing structural support (vertically not laterally) to the aquarium. A perimeter stand works exactly the same as a solid top stand since only the perimeter is actually touching the stand. A solid top stand on a framed aquarium is just a waste of material. But it does allow you to slide the tank on and off easier and they do have some aesthetic appeal. Especially if the stand is meant to fit more than one footprint aquarium.

I hope that clears things up. Good luck with your new tank.

Andy Hudson
Central Aquatics (Aqueon, Oceanic, Coralife, Kent, and Zilla)
Research and Development
President Milwaukee Aquarium Society
 

Rbishop

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:iagree:
 
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