I don't usually have this happen, but the answer I just posted also applies directly to you:

I'm out the door, so I can't respond at length, but the stickied posts in this section [ http://www.poolforum.com/pf2/forumdisplay.php?175 ] will help, especially this one:

Super Simple Pool Chemistry Recipe - http://www.poolforum.com/pf2/showthread.php?17055
Good luck!