sealing

Hi all, long time reader first time posting! I recently found a unique cylindrical glass container that I would love to turn into a small (4 gal or so) neocaridina shrimp tank or even possibly just a plant tank, but it has a piece of metal that it sits in and acts as the bottom of the container...

I recently bought a new fish tank and there are these weird white balls forming in the corners of the tank. Is this cause for alarm?

Picked up a 180g second hand a couple days ago. Previous owner had just drained it a week prior (allegedly) after upgrading. According to him no leaks or issues etc. Upon inspection a couple spots have some silicone that doesn’t look great but for the most part it is good. Whether they leak or...