With a SWG the chlorine gas never leaves the SWG cell. With conventional chlorine gas you have a chlorine gas tank, which can leak. Chlorine gas has gotten less popular with commercial pools over the years because chlorine gas leaks can kill people while liquid chlorine leaks are a mess but don't generally kill people.
michael89156, a SWG, or Liquidator, or bleach pump will all meet your requirements for less money and far more safely than a chlorine gas system.