Everything I had read says as long as the only, "ONLY" ingredient is VOC then it is safe to use for aquariums. I have used GE Silicone I, not II as it has added junk in it. Granted the experiment was only with about a 2.5 gallon tank but it is 18 inches tall and was a total mess before I finished but it never leaked!
I don't know if this will be overkill but when I build the tank I want over 75 gallons, I will be building a frame that will be for all corners, bottom and the top out of wood. When I place the pieces of glass, I will be siliconing the inside of the wood, between the panes of glass and the inside. The wood will hold the glass in place while the silicone dries and offer support for the taller, wider tank I want to make. 24x24x?? is the tank size I want to make so it has to have a very secure seal on the bottom to keep the glass in place.
