Home Depot has muriatic acid. It's great for pools and takes concrete off metal.
i used some in my bathroom last week. shit aint no joke either. So strong i ran out that bitch not wanting to breathe the vapors.
off topic, but somebody oughta caption this the next time some dude gets dunked on
“I looked in the mirror and was so angry. I wanted to know where my face was so I could go pick it up, put it back on and head straight back to my old life.”