Zep Acidic Toilet Bowl Cleaner - 1 Gallon (Case of 4) R43710 - Removes Hard Water Stains

I purchased this ZEP Acidic toilet bowl cleaner on a whim. I was cleaning a house that had been vacant for more than 10 years. The toilets had more than a decade of hard water stains, rust, lime, calcium, and "unidentifiable" residue buildup cemented to them. I was certain the toilets would have to be replaced but felt I needed to at least try to clean them first so I wouldn't feel like a quitter. I used one application of this ZEP acidic toilet bowl cleaner and waited for 5 minutes - the stains started coming off! I was absolutely stunned. So, of course, I flushed the water down and tried another application right away. Again, I waited 5 minutes and this time almost all the stains were gone! I was gobsmacked. I ran out and got a toilet bowl brush and when I got back I tried a third application. Again, I waited 5 minutes but this time I scrubbed for about a minute. And what do know, the toilet bowl looked brand new!! I was amazed. This stuff is absolutely worth every single penny!! Not sure how it is rated so low BUT YOU HAVE TO TRY IT FOR YOURSELF!! It is amazing.