On 29/09/17 17:37, Andy Burns wrote:
Dan S. MacAbre wrote:

I think the bought stuff contains citric acid

Some (e.g. kilrock) is formic acid, the gentler ones for coffee machines
use lactic acid.


In my experience, formic acid is damn efficient - much more than acetic.

However, for food usage (eg kettles) and bathroom cleaning, I find
citric to be the best - moderately powerful and not toxic.