Removing/cleaning glass haze near water line?

I picked up a tank previously used for sal****er. What i have noticed
in the top 1" below the top frame, is that the glass is hazy. It's
really smooth inside, so it doesn't appear to have hard water crusting.
Does anyone know how to remove this?? I would like to get back into
new shape. I'm guessing it maybe from the sal****er minerals/salts/etc
wearing on the glass near the water line.

I've tried too paste ....trying to buff it out, I also used a dremel
with a buffing wheel + toothpaste. Both work ever so slightly. Any
suggestions to buff this out faster?
Thanks!!

-joe