I have always tried to buy liquid shock from our local pool store. If we're out & don't have time to make the drive, we'll pickup liquid chlorine from Krogers or Wal-Mart. Powdered when it's the only option. Over the years I've wondered what the difference is between the two but never actually researched it. I assumed that shock had more to it, was more powerful than chlorine. Today, after adding my two gallons of shock to the pool, I finally decided to Google it & from what I'm reading, they seem to be the same thing! Liquid shock is nothing more than liquid chlorine? Does anyone have a definitive answer to the differences, if there are any? Thanks!!