Looking To Build My First Large Aquarium.

im about to put together my tank also (not that large but still decent)
RTV silcone is what you will want to use. Ebay seller ZoroTools has the best pricing on tubes. RTV comes in clear or black.

also on a tank that big i would recommend a upper ero brace and also bracing inside the tank on the bottom. Also glass thickness i would go overboard on rather than cut corners.

i have chose to put the tank together with a not so used method of direct injection. read up on the difference between direct injection and traditional and make your own call on what you feel more comfortable with.

a tank the size you want to build is no joke and if something fails could really turn into a disaster or worse if it happens when someone is standing there could leave injury. Read read read before you even attempt.