I had a slop sink installed in my laundry room a few years ago, and for quite awhile when we turn on the facets I can hear loud rattling in the pipes. sounds like a gorilla is shaking the pipes. We normally never use the faucet but when we do i get a bit scary. Any ideas what maybe the problem?

Also, i get calcium build up around my shower heads and was wondering if using magnets around the pipes can help break down the water to alleviate this problem?

Thank you,