Just go to the Canadian Tire "Pool Cleaning Supplies" section and purchase a bottle of Muriatic Acid.
If you want to play around a bit, just for fun on a few bits and pieces of scrap steel.
Get a can of Draino, add some salt, vinegar, and pour boiling water onto it. Use that mixture and see what happens.
Not as fast/dark as the acid types but it works
The question was where to get the Nitric acid. Pretty sure CT does not have it.