So what if I cut down on height, but added width? So, instead of 8'x4'x4' I went 8'x5'x3'..Would that affect glass thickness in a positive way, negative way, or make no difference? I am thinking that with this build, I may want to go less tall as the fish is a top dwelling fish, and once he is out of there I want to put some nice rays in there so wider is better than tall all the way around in this case...It adds some extra cuts but I could just have HD cut them down to 3'x8' sheets for free and then I have the same amount of work to do..I will just have to buy an extra piece of plywood is all..If the 6" border at the bottom is veneer (and I consider moulding to be basically veneer), then for determining glass thickness it's still 48 inches deep. That's because veneer isn't reinforcing the bottom and the glass at 48" depth is under unreinforced pressure. If on the other hand it's really strongly built to restrain the glass (not simply cover it), that is, the border is physically supporting the glass against pushing out, then the "effective" depth is 42". That reduces the thickness needed to 23mm, (although not 19mm.)
I believe that adding a vertical piece of wood dead center that strongly reinforces the center has the effect of reducing the pressure on the glass as if it's half as wide. That would reduce the 23mm to 17mm. I can't tell you exactly how that has to be done in order to get that effect. I know that people have built large deep tanks and used that method to have tall, rectangular windows with relatively thin glass by keeping the width to a minimum. For example, if you had two 4' by 4' pieces of glass, built them into the tank correctly and had a strong 6" border at the bottom, you could probably use thinner glass like 17mm.
People of course often don't want that strip because it breaks the vision. Personally, I would opt for a longer or wider tank with less depth because I prefer no obstructions. Ultimately, unless you need the depth, it tends to be the choice people make. Four feet deep of course also adds a serious issue in terms of cleaning and maintenance.
So if I did an outside "trim" it would basically add no structural support..What if I framed the inside of the tank with 2x4s? that would surely add support and stability to the tank. Would that help reduce the outward pressure of the glass? Or would I have to frame the outside of the tank with 2x4s to do that?
I am starting to understand this more and more every time we discuss it and I will get it eventually..I typically have to see it to understand it, so I am building small mock-ups out of cardboard to understand what you are telling me..haha
I am so ready to get started on this build!!.and since the overall end project is going to end up here at the store, the store is going to be paying for the first two builds..
Let me know what you think.