On Sunday, December 23, 2018 at 10:44:06 PM UTC-5, Martin wrote:
replying to notbob, Martin wrote:
Just buy some good old brick acid (cement cleaner from your local builders
merchant) leave over night and flush! Doesnt matter how bad/old the
limescale is, it just removes it over night...


--
for full context, visit https://www.homeownershub.com/mainte...its-743699-.ht

Otherwise known as hydrochloric or muriatic acid. In my experience, it works
in minutes.