First off, rather than 4 deformed 1.5” uaru for $18 each, 3 larger nice 3.5” ones for $23 each would be a better deal if you’re on a budget.
As for the resealing a large tank, how you do it all depends on what’s wrong with it but it’s not as simple as it would seem. And if you wanted to do it right and make certain it doesn’t leak, you’ll want to take the whole pane off, clean up the edges, and seal it back properly.
If you’re uncertain what studs are and don’t know the construction of the building, the last thing you would want to do is put a huge tank on the 5th floor, especially one that’s leaking which you plan on “fixing” by simply resealing the inside corners. If that bursts or leaks, water will run down all 5 floors and cause lots of damage. Even if it doesn’t, the floor may not be able to handle the weight. Typically, you can comfortably put a 50 gallon tank on an upper floor with wood studs without thinking twice but anything beyond that, you’ll have to think it through carefully. There is the weight of the tank, stand, water, gravel, decorations, and more you’ll have to account for.
It’s faulty logic to think that just because a bathtub can be on the top floor, a 220 gallon tank can too. Like someone said, there is extra support where builders place bathtubs and they are not constantly full of water. Other areas of the floor may not be rated to handle that sort of load. It’s also a logically fallacy to think you can do something because someone else has with no issues. Even if someone put a 500 gallon on an upper floor and is fine doesn’t mean you can or that they won’t eventually have issues. You need to look into it and do more research and planning on where you put a huge tank.
I’m not trying to give you a hard time and only spent the time replying in hopes of steering you away from a potential disaster. Take your time and double check everything if you plan on putting a large tank, including your 120 gallon, on the 5th floor. Water damage is extremely costly to repair.
