It's been two weeks since I've received salt, plants, and rocks from Mustafa, and since several days ago, a wispy... thing (for lack of a better term) appeared in my tank. I've attached images in this post. I can swirl the water around it and it'll dissipate, but the next day it comes back in the exact same location, in the same shape. I was wondering what this could be. Some sort of undissolved salt? Calcium carbonate?
It's probably some kind of small bacterial bloom. It will go away after some time after the bacteria eat up whatever nutrients are in the water. I wouldn't worry about it.