There are a variety of cleaners on the market today made specifically for granite (some even have sealers built in) however, they are not required. Granite can be cleaned with dish soap and water and then dried with a clean cloth to avoid residue buildup. Cleaners that have a neutral ph can be used as well such as Glass Plus. You want to avoid cleaners that have ammonia or other acidic bases. They will not hurt the granite itself but over time can strip away the sealer.