See our project on cleaning grout when hard. There is a tool in there called a grout rake, its used to literally rake out the existing grout so you can put in new.
DIY how to tutorial projects and guides - Did you know we have a DIY Projects section? Well, if no, then we certainly do! Within this area of our site have literally hundreds of how-to guides and tutorials that cover a huge range of home improvement tasks. Each page also comes with pictures and a video to make completing those jobs even easier!