>>182It may not be obvious in the picture, but I do not believe that the surface of the tub under that paint is actually white (therefore, I don't believe acid is going to help).
It looks to me like every time a resident moved from the apartment, the maintenance guys came in and covered the whole tub over with paint or some other material to make it look white, and over time that material has come off.
You can see that different parts of the tub are different tones of white, and I believe that is the reason why.
>>183I'm pretty sure replacing the tub is outside the scope of what I'm going to be able to do in an apartment.