i have a jbj 12g nano i believe from the sand blowing around and settling i have white residue on the inside glass that doesn't come off with the supplied cleaner ??
Scratching my head….If it is a new tank, and you mixed your saltwater in it… the residue should dissolve on its own in a day or two. In the future mix your salt in a separate tub before you add it to the tank.
I have a small spot on the inside of mine is well. It's sticky like sticker residue. I haven't really tried getting it off yet as I'm not sure what the best way to do it would be. Fingernail doesn't get it off.