We just put in a new pool, with our package was included a free one month of pool cleaning so they could see how things were running. On the 3rd cleaning, the guy put in soda ashe, told me not to use the pool for 2 hours. The whole pool was cloudy and looked like a container or milk for two days, we finally called them and was told the guy should not have used that with our type of pool filter. They came out and vaccumed it up and returned the clarity of the water. on the 5th week after the pool was running, I noticed a white line around the pool but mostly really bad around the water feature which is 3 sheers with a stone wall behind it. The pool store told me to use pumice stone and I did but it didn't remove this stain. I thought this was really unusual given the age of the pool and the fact that I managed the chemicals every day to keep them balanced. Added acid when needed etc. We live in arizona and have hard water but this is not what our neighbors who have pools experience, nor this qucikly. The pool builder came out and they are going to blast the stain off the tile and then treat it with a sealer. I still think the wall behind the fountains are causing the problem but the pool company says no, they also have no solution at this point to keep this problem from reoccuring. There was one week right after I added Acid that there were calcium pebbles all over the top of the pool and I skimmed them off. If we have this cleaned I am still not sure how to keep this from happening again.