I´m planning to build a tank that will be 200cm long, about 6'6" and 55cm tall, 22". It will be an open tank and most of all I whant to have it ADA style with no braces. It´s been recomennded to me to have glass beams siliconed to the top of the long sides of the tank to stop the glass from bending under the pressure of the water.
My question is; is the tank to big to be built without these supports? How thick glass would I need to be able to build a tank this size without supports?
3/4" is a min I'd use.
If you have over glue on the edges, you will also gain some strength, but it will not look as nice as some tanks that have the the no edge trim on th silicone seams. Trade off there.
6.5 ft x 22 tall is not much different than a typical 180 like I have.
Height adds a lot more stress to the bond.
Special silicone glues and all that, that's baloney, do not fall for any mumbo there. They are just pulling your leg.
This is going to be a very heavy tank, 4-5 people and some Glass moving suction disc(4 or so) will be needed.
3/4" will not bow, nor is that a huge issue at this thickness either.
even with a laser level, I cannot detect any bow on 3/4" over 6ft distance.
1" is extremely heavy.
It's over kill, but you might consider having that made on site.
This is my tank which is close to what you are after, it's 3/4" or 19mm.
ADA's is thinner than this and the silicone is cut to the edge, looks prettier, but...........you lose about 2-4mm of glue surface and no amount of special glue can make up for that area.
A few corner bracings or Euro style might be an added safety feature for you, but I'd not go more than 3/4" really.
12mm is out of the question.
16mm is also rather thin IME.
Go 18-20mm range. The bracing is more for insurance.
If you do 20mm and do not trim the silicone to the absolute corner, then you likely will not ever need euro bracing of any type.
Just make sure you never move the tank again