Second, the four-thick glass is ordinary glass. As long as there is no serious quality problem with ordinary glass, it is no problem to make a 30cm square fish tank.
Thirdly, the strength of the glass glue is not determined by its thickness, but by the smoothness of the glass incision and the tightness of the glass glue at the sticking position. If you can see that the glass glue at the paste position is too thick, it means that the fish tank is not strong because the glue is tough. Of course, if the glass glue is too thick, it will not burst, but it will easily leak. Therefore, the glass glue does not need to be too thick at the incision position, as long as it is evenly applied and firmly pressed during curing, there will be no problem. My cylinder is 1.5m, less than1mm.
Fourthly, what I want to say is that large fish tanks are generally internally solidified, which is what we often call lacing. External lacing is rare. According to the mechanical characteristics, the internal lacing has high curing strength and anti-seepage function.
Of course, if your fish tank doesn't need to be solidified with anything, it's too small. As long as there is no big problem in appearance and no water leakage, you can use it with confidence. No problem.