Never use Muriatic Acid. You can be killed or left brain dead. Muriatic Acid reacts violently with sulphur which parts of Michigan are known to have.
If you do a search for Nu-Well tablets here you will find a place in Holland Mich that sells these tablets.
Once you have put them in the well it is important to keep a steady stream of water running down the well to dissolve the tablets. Otherwise they will just sit there and do nothing.