I have pool so use muriatic acid a lot to clean up calcium deposits from pretty much anything reef related. Use it straight out of a syringe or diluted in water. As long as you're careful with it it is not a problem, only stings if you have cuts or scrapes on your hands. Definitely keep it away from anything with bleach in it, like comet cleanser, shower type cleaners, as that will create chlorine gas which is not nice.