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