Remember, always add acid to water, NOT the other way!

Muriatic Acid is simply Hydrochloric Acid, use standard precautions. This stuff will sting and tear up your skin, vapors will sting the heck out of your lungs - use in well ventilated area. I used this stuff in pool maintenance and was fairly familiar with it. If you have never used it, be careful and take precautions: Gloves, eye protection, well ventilated area, possibly a respirator (esp. if you have respiratory problems).

Sorry for the soap box - but this stuff ain't just strong vinegar ;)