YOur pool was just acid washed which should have gotten rid of the calcium! That is one of the purposes of acid washing. By adding 7 gal of acid to your pool they are in effect doing a second acid wash. Sounds a bit strange to me. I would use washing soda (soda ash) to bring the pH back in line and I would use a testkit with a base demand test (like the Taylor k-2006) to see just how much to add. Once the pH is in line you can procede with the rest of your water balancing!