What kind of shock did they buy? We are finding out this year that HTH has gone over to the "dark side" as Ben calls it and their products are not very good any more. You could just use bleach.

While you are filling it, you might want to go ahead and drizzle some bleach in there. It doesn't take long for an unchlorinated pool to have an algae bloom brewing. Just walk around the perimeter of the pool and slowly drizzle some in being careful not to splash you or the liner. Then take a clean broom or oar or something and stir it around.

You must use pool sand for the filter. Play sand or other types that you might buy at Lowe's or whatever will NOT work.