Complete grout removal can be an extremely tedious job, if not done with the proper tools or experience. Their are grout saws that can be used but thy are difficult to use , you can purchase a dremmel with small carbide wheels and grind it out , but this method is usually only good for minor repairs.It appears that JJ gave you some good advice. You should also use a grout that is polymere modified. And if you want you can hire us to do the job for you we are grout and ceramic tile restoration and installation contractors we do this type of complete grout removal every day . We are in NY so we are just a ferry ride away. Good luck Michael C. Malizia The Grout Dye Company http:/members.aol.com/groutdye