Hi - don't use muratic acid on aluminum parts
- it will eat them up (speaking from experience...).
I use the straight strength available at hardware
stores - I think it is about 34%.
Someone mentioned about a 2 to 3 minute soak for copper piping and this is a good number - it's what I used.
For heavy copper/bronze or steel
parts I wouldn't go over 5 to 6 minutes before checking to see how things are going. Once the bubbling has stopped, most everything has been disolved.
Neutralize and flush with LOTS of fresh water.
Do NOT breath the fumes given off by the acid!!!!! They will really damage your airways and lungs. This is a kick-ass chemical, so be REALLY careful using it. Gloves and face mask with proper chemical elements in it are recommended too!