It's calcium carbonate so in a pool that is already mostly saturated with calcium carbonate it's going to take a long time to dissolve. It would be similar to adding a combination of calcium chloride to raise calcium hardness along with sodium carbonate to raise both pH and TA. It's that latter part that will go up substantially and that you don't want. Even if you add acid to keep the pH down, your TA will go way up. And yes, you could lower that with substantial effort using more acid and aeration, but really this isn't a good idea. Just get some calcium chloride if you need to raise the CH -- it's relatively inexpensive if you get the Peladow or Dowflake as described in the Pool School.