Bingo, those raise the pH and GH...although usually not that high. How new and how much do you have in what volume of water?
i've had the stones for awhile. they were in the same setup before i rescaped. id say theyve been submerged in my possession for about 4 months total. i boiled them before adding them. i didnt have a kh or gh test back then so i couldnt tell you what the water was like.