Originally Posted by
apt220
Muriatic acid would be better to achieve what you want. Just be careful. It's concentrated hydrochloric acid. Wear eye protection and glvoes; and always add acid to water, not the other way around. Use at your own risk. I use this stuff to clean my pumps and to clean rock. It works relatively fast because it's strong.
There will still likely be some film that you need to brush away. It's not going to make it sparkling clean, but it will dissolve the calcium in the pipes.
It's found in the paint section at walmart or HD.