With a big tank like that you have to reseal it anyway.
I purchased a 225 gallon aquarium used about 3 years ago. Sadly I had to sell it when I moved into my current house.
The standard door width for interior residential doors is between 2'-4" to 2'-8". You do occasionally see ext. width inside but My house is very average in terms of its architecture.
My aquarium was 5'-0"X3'-0"X2'-0". with the 3 feet being the width.
When I got the tank I didn't trust the seals on an old 3 foot wide tank so I actually came here much like you to get some advice.
First off you need aquarium safe silicone, Home depot even sells them so that shouldnt be too hard. I think I got 3 tubes and I ended up having a little to spare.
Get some scraper blades and carefully remove all silicone from every surface.
Silicone won't adhere to other silicone (with the exception of when its applied at the same time)
when your tank is 100% silicone free (and in pieces) thats when you can begin resealing.
make sure you don't reseal the whole tank right away, its good to do one piece each day.
you can also use clamps to hold the glass plumb and at the correct angle.
I had a large cross brace piece in the center because of the width, I used a bucket to stop it from sagging.
The width lead to the production of my tank to be different than the typical store bought kind. It had a single solid base piece of glass, but then thin long bracing around the entire perimiter. The base glass was adhered to both the braces and the side pieces.
I was only about 20 at the time and it was the first aquarium over 50g that I ever owned. So it was a real undertaking but The tank was in great condition for years after the reseal up until I sold it.
Good luck with your project and if you have any questions about how I did specific things I would be happy to help you.
Also worthy of note is that my tank had 1/2" thick glass. very heavy and a single side piece (2'-0"X3'-0") cost $300 canadian. and that was when our dollar was in a good place lol.
