If it's one pound per 10,000 gallons, then that may drop the pH to around 7.0, but if it's a lot more than that then it could lower the pH more than you would want and low pH isn't good for vinyl liners. It's nowhere near as bad as throwing a Trichlor puck into the pool resting on the liner, but it will lower the pH and you'll need to aerate the water to get the pH back up if you want the TA to remain the same. Otherwise, if you use Borax or other base to raise the pH, the TA will rise as well. We have a bunch of threads on dry ice -- do a search (using Google search at the bottom of the TFP screen) on "dry ice".